LGBTQ is an umbrella term for homosexuals. bisexuals, trans people and people with queer expressions and identities.
The L,G and B are about sexual orientation; who you have the ability to fall in love with or become attracted to.
The T is about how you define and express your gender.
Queer can be about sexual orientation, gender identity, relationships and sexual practices, but it can also be an expression of a critical attitude towards existing norms.