Most inexpensive fans come with Ball Bearings which are noisier in operation, have a comparatively lesser lifetime. Some others come with the Fluid Bearing which're expensive, silent in operation and lasts longer.
There're fans with Sleeve Bearing which are a notch inexpensive than the ball bearing fans itself but cannot be mounted in any other position apart from vertical hence finds limited applications. Heat endurance of sleeve bearing fans are low i.e with elevated temperatures, their life expectancy comes down drastically and becomes noisier as it ages.
Magnetic Bearings uses the principle of magnetic levitation to support the load without a physical contact thus resulting in zero friction. They're expensive and Sunon has patented the tech under the name of Maglev with quite a few fans under their branding. Vapo bearing IINM is the tech used in Maglev fans.
SSO Bearings (Self Stabilised Oil Pressure) are patented by Noctua IINM. It's basically another fluid bearing but has an additional magnet which aids in the self-stabilisation of the central rotor of the fan. Results in an even quieter operation and lasts longer than conventional FBs.
UFO Bearings - no clue. Have seen them mostly on Zerotherm fans.
What exactly are you looking for? Fans on a limited budget? We can help you if you could tell us the budget, the type of application you're targeting and noise levels you're willing to tolerate.