Questions about legal consumption and possession of CBD

As a Canadian I am used to a difference economy/market when it comes to the cannabis plant.

Here the government stores call it cannabis, (which has THC in it and that is federally illegal in the USA), we have hemp products which is just paper, clothes, biodegradable containers, etc.

Some of the US sites used the words “hemp flower” “raw leaves” “THCA products” and “Hemp-derived CBD”

……. What are they talking about when they say hemp flower, hemp derived?

We also have CBD + CBG + CBN , none of those have any psychoactive properties so surely theyre legal in all states?

I just want to learn if I can legally bring over CBD/CBG/CBN capsules for my mum ——that have absolutely no THC