Old Testament v. Tanakh v. Torah

Sorry if this sounds like rambling in advance, I don’t know what I don’t know.

After watching tons of videos on theological studies I’ve decided I’m really interested in reading the abrahamic holy books. I grew up in both the Russian Orthodox and then non-denominational Christian church (very big jump in theological views) but landed agnostic. At least when most people think of Judaism, they think Torah, which I found is the first 5 books of the old testament or vice versa, being that Judaism came first, and that the Tanakh would be like the entirety of the Old Testament.

My questions are, a) is this an accurate statement, b) if I’m going into it as more of an education is the Torah a better starting point or would it be incomplete without the Tanakh and c) how different (if anyone knows) is the Jewish holy book from the Old Testament of Christianity?

**edit: I see the moderator bots message, and mean no disrespect in my questions, simply interested in learning.