You bought one Nexus phone and you're wondering about the SIM card size? Great. You can find the Nexus 5 SIM card info bellow.
Nexus is the LG brand phone. Samsung has Galaxies. Apple has iPhones. LG also has a Nexus. At least there was. I guess they're not making any new calls.
LG brand makes the phone. But he doesn't make a new phone under the name of Nexus. Meanwhile, the Google brand has a phone called Nexus. Both have sim card sizes. Therefore, I do not think there will be great information pollution.