Many versions exist containing differences that merely change the direction of the letters. LGBT and GLBT are the most common versions and the ones most frequently noticed and used.

Although indistinguishable in meaning, LGBT might have a more feminist meaning if compared to GLBT as it emplaces the “L” (for lesbian) first. When it does not include transgender people it is sometimes abbreviated to LGB.

LGBT might as well contain extra “Q” for queer or questioning (sexuality and gender); questioning which is sometimes shortened with a question mark and occasionally used to denote anyone not literally L, G, B either T. In this case the acronym would then extend to LGBTQ or either LGBTQQ.

Other variants/acronym:

LGBTI : Lesbian, Gay, Bisexual, Transgender/Transexual and Intersexed.

SGL: Same sex loving.

LGBTTQQIAAP: Lesbian, Gay, Bisexual, Transgender, Transsexual, Queer, Questioning, Intersex,Asexual, Ally, Pansexual.

QUILTBAG : Queer and Questioning, Intersex, Lesbian, Transgender and Transsexual and Two-Spirit, Bisexual, Asexual and Ally, and Gay and Genderqueer.

FABGLITTER : Fetish (such as the BDSM lifestyle community), Allies or poly-Amorous (as in Polyamorous couples), Bisexual, Gay, Lesbian, Intersexed, Transgender, Transsexual, Engendering Revolution or inter-Racial attraction.

The information compiled in this article was obtained from the following sources:
Wikipedia
Mentalhelp