By all accounts, there exist two major divisions within Freemasonry. These are more politely referred to as Regular and Liberal Freemasonry. Coming from the so-called regular side, you can also hear a lot of uncivil comparisons. Terms ranging from Irregular and Clandestine to "bogus" get bandied about and none of it is done with a shred of courtesy. For an institution claiming to focus on Universal Brotherhood, morals and ethics; an institution claiming to take good men and make them better, this sure falls far from achieving its stated goals.
If we listen to those who speak on behalf of mainstream Freemasonry in the US, that is the offspring of the UGLE, you will hear a great deal of legalistic arguments that would appeal to a lawyer, but not appropriate to philosophers. One might be forgiven for smelling excuses and justifications rather than explanations. In fairness to most "regular" masons, they have been indoctrinated to accept this approach on faith, and rarely have been called on to examine it rationally. The explanations focus on legalistic definitions and details. The dogmatic details of mainstream masonry define any Masonic organization as legitimate if it possesses recognition from the UGLE or other organizations which themselves were recognized by the UGLE. These arguments are based on political power and control. This is especially ironic as the supposed original lodges of the first London Grand Lodge would have been unable to meet the qualifications demanded by mainstream masonry themselves. There is no element to any of these definitions which reflect a concern with ethics, morals, or personal development, which supposedly are the main purpose of Freemasonry in general, and due to its rejection of esoteric interests, of mainstream freemasonry more narrowly.
I will not expend energy attempting to dissect this argument according to its own perspective. I do not view it as particularly relevant. I am not a lawyer, but further, such arguments are concerned with temporal and political control, and thus do not bear any relation to the stated purpose of the institution. For that reason, I do not view such legalistic foundations as having any real merit or being worthy of serious consideration. I've never seen any of the negative remarks offered about non-mainstream lodges to have any merit either. The so-called "bogus" masons I have met face to face have largely been at least as moral, ethical, and considerate of others as their mainstream brethren.
This leaves us asking what is the real difference here. If one ignores the denominational bigotry, we can see, from an historical perspective that there was a meta-principle which divides "Liberal" and "Regular" Freemasonry. This difference is most clearly identified in historical perspective and has nothing to do with dogmatic practices such as biases surrounding gender, religious, racial, or sexual preferences, none of which ultimately should have any place in intelligent Freemasonry.
The main difference can be identified by looking at the original principles of Freemasonry and how they evolved over time. Whatever it was before the non-operative membership began to dominate, and I do not accept the theory that "gentlemen" masons were responsible for the creation of speculative masonry, it makes rather more sense to view the speculative, philosophical, and symbolic aspects of operative masonic lodges were precisely what drew "gentlemen" freemasons to them, by the 17th century it appeared to be fairly cosmopolitan in character. This cosmopolitan attitude is clearly demonstrated in the Freemasonry which grew both before and after the arrival of Jacobite Higher Degrees from Scotland and Ireland in the first half of the 18th Century in France. It was this cosmopolitan character with its aesthetics and values which inspired enlightenment philosophy, political speculation, and sparked ideas which led to modern democracy, the opposition to slavery, and eventually modern ideals of universal suffrage and equality.
It was this Freemasonry which inspired people to revolt against monarchy and institute the democratic governments of the United States, France, Haiti, and the Bolivarian Revolutions throughout Latin America, as well as less successful attempts such as that of the United Irishmen (Éireannaigh Aontaithe) of 1798. It was also this cosmopolitan strand of Freemasonry which became embedded in the Memphis Misraim and Carbonari of Giuseppe Garibaldi.
The foundation of the Grand Lodge in London, in the year of 1717 was clearly a political act of self preservation, assuming it doesn't in fact represent a myth. Freemasonry was closely associated with Scotland and hence the Jacobites. In the new Hanoverian world, to be associated with Freemasonry was tantamount to demonstrating loyalty to the crown rather than the Hanoverian usurper, George I. That was a dangerous if not fatal choice, and so a non-jacobite history had to be rapidly invented, no matter how spurious it may in fact have been. Anderson's claim that the event even occurred needs to be re-evaluated before their 300th anniversary in 2017, but the outcome, regardless of the legitimacy of the claims, was a new form of Freemasonry under Hanoverian authority. The Hanoverian kings lost no time putting this new institution to work as an instrument of its new efforts at empire building. It supported the monarchy, in opposition to the cosmopolitan forms which continued to exist on the continent, moving rapidly to invalidate opposition to its authority and to its monopoly on the claim of authenticity.
The masonic influence on the revolution in what was to become the United States stemmed from the continental Freemasonry of Benjamin Franklin and his French masonry of Loge Les Neuf Sœurs, far more than the English Freemasonry of Washington. It was liberally assisted by masons among the radical Irish later forced to escape after the aborted Irish revolution of 1798, those disenchanted Scots Jacobites who came to the Americas just as others helped forge High Degree Masonry on the continent, and people such as Joseph Warren.
This, rather than the various dogmatic issues usually pointed to, is what created the difference between "Liberal" and "Regular" Freemasonry ~ the radical re-visioning of society and our scientific and political institutions which had always been the true landmarks of Freemasonry rather than the support of the institutional status quo of pre-Enlightenment Europe.
Louis Amiable, Une loge maçonnique d'avant 1789, la loge des Neuf Sœurs (Les Editions Maçonnique de France, Paris 1989)
Jessica L. Harland-Jacobs, Builders of Empire: Freemasons and British Imperialism, 1717-1927. (UNC Press, Chapel Hill 2007)
Margaret C. Jacob, The Radical Enlightenment: Pantheists, Freemasons and Republicans (Cornerstone Book Publishers, Lafayette, La. 1981 & 2006)
David S. Wilson, United Irishmen, United States: Immigrant Radicals in the Early Republic (Cornell, Ithica, NY 1998)