You should have received both an active AND a passive FOB. With only 1 FOB, if you lose it or it is completely destroyed, you are in for a MAJOR expense! (With no FOB, no additional FOB can be programmed and the computer will need to be replaced, which is lots of $$$$). So make sure you get some additional FOBS (of either type) as soon as possible.
The passive-only FOB is smaller/thinner/lighter and much cheaper. But it is also less convenient to use.
As has already been posted, the large FOB (with battery) is a combination active and passive FOB. If the battery is dead or circuitry is destroyed, the active part will not work, but you can still use it to start the bike with the passive portion by holding it against the magic spot for a moment, north of the stove key, then pressing down on the stove key.