Exactly,
* some have greater power (and consequently, usually lesser battery life)
* most are one speed, but some are multispeed
* most are "standard" size and are compatible with most dildos and other bullet-holding toys, while some are larger, longer, or smaller
* most are quite loud and buzzy, but some are quieter and more rumbly
* some are made of better materials than others
* and some are just made to last longer