Yeah, basically. Standard is a rotating format-sets go in and out of legality with it. Right now, Theros block (which includes Theros, Born of the Gods, and Journey into Nyx), Magic 2015 Core Set, and Khans of Tarkir are legal in Standard. Modern is a non-rotating format, so once a set becomes legal in it, it doesn't rotate out. Any set from Eighth Edition onwards, including everything in Standard, are legal. So the card pool is enormous in Modern when compared to Standard.
Even so, Modern only encompasses a fraction of the total amount of cards printed. After Modern, you have Vintage and Legacy, which are called "eternal" formats, because with a few bans and exceptions (UN-sets, etc), every card ever printed is legal in the format. The same's true with Commander, which a lot of us play here. But Commander is more of a casual format, so I'm not sure if it really counts-it's not technically an official format like the other four are.