How to find what model of Galaxy Nexus I have?
"Galaxy Nexus" is the full name of your model. The Nexus 4, Nexus 7, etc are all different models entirely. The only portion of the naming convention that is shared is Nexus; the "Galaxy" moniker is one that Samsung likes to use for its phones, and thus they applied it to one of the Nexus phones that they produced. If you were to refer to the line of devices as a group, you would therefore call them Nexus devices, not Galaxy Nexus devices, as the Galaxy Nexus is simply one model in the Nexus line.

This Wikipedia article has a list of all Nexus devices released to date, along with links to pages specific to those devices. As you can see, "Galaxy Nexus" is listed between its predecessor (the Nexus S) and its successor (the Nexus 4). The HSPA+ variant sold on Google Play was given the codename "maguro". There are also other variants of the Galaxy Nexus for other carriers, so you can generally know which variant you have based on which carrier you use it with (or purchased it from).