what is gender identity dysphora?

I'm pretty sure they are the same thing.
Transgender is the pop culture name, while GID is the medical name
At least that is what I was lead to believe

 

Gender Identity Disorder (GID) is the outdated medical term classifying all people with a different gender identity than the sex they were assigned at birth based solely on genitalia as having a "disorder".

After a long time, in I think 2013 (the year they switched from using the DSM-4 to the DSM-5, the book for mental/anxiety/depressive disorders and stuff) they made a new term that worked for a bit. Now it's Gender Dysphoria, which is just the horrible feeling one gets when their gender identity differs from their birth sex, like looking in the mirror and feeling like jumping off a bridge into a lion's mouth because of said differing gender identity from physical characteristics; I like to think of it as a depression/anxiety thing instead of a full-on mental disorder (though depression and anxiety are classified "mental" disorders, I don't like using the word because it makes us sound crazy. :\).

Not everyone who Is transgender, as in having a different gender identity as their birth sex, has Gender Dysphoria. It is just that Gender Dysphoria is the big tell-tale sign of being transgender (or in some people's words, transsexual (I think the word just sounds harsh when you say it, too many hard letters, I don't really use it that much)).

Sources; having to correct my psych teacher on using the DSM-4 AND equating differing Gender identities to homosexuality, I had to do some research. I mean, I knew what I felt, but I also had to look at it from the DSM-5 point of view.

 

Oh, well. Courtney beat me to it, and gave a better answer. So ignore mine if you want. ^^

Spoiler

CadutiMorte, you're not wrong, but you're not exactly right either. (By the way, I love your username.)
Transgenderism is where your sex and gender don't match. This is an umbrella term for any non-binary or transgender person.
Gender Identity Disorder, or GID, is the same thing as transgenderism, except it can refer to all facets of transgenderism, not just transgenderism itself. GID can refer to dysphoria, the fact that you are transgender or the fact that you are questioning (etc.). It is also a medical term. Used correctly, it mainly refers to the fact that someone is trans*, but medical practitioners don't have degrees in gender studies, hence the lengthy text above.
Gender dysphoria, which is what OP was asking about, is where the disparity between sex and gender causes distress. This usually manifests itself as confusion, or depression.

 

Thank you, Hazel. I literally just woke up before checking EC, I couldn't think clearly, and was trying to word it the best I could; I'd like to combine both our definitions, mostly mine and everything after "It's also a medical condition" in yours.

I forgot to add "distress" and stuff. I also like the part about not having degrees in gender studies.

If you can't tell, I'm still a little tired.

I need to find a way to sleep better... =_=