mountain bikes have a "flat" handlebar that is mostly straight from end to end.
They also have dropper posts - this basically converts a bicycle seat into an office chair. A handlebar lever you can pull will let the seat move up and down hydraulically and when you release it it stays in that position.
People use it to pedal normally with the seat up, but on tricky trails you can drop the seat down out of your way.
back to handlebars, drop bars are what road bikes have. They are the curled handlebars that look like a C from the side. If you lean forward, you can grab them by the "drops" and aerodynamically pedal harder.
Thanks. The presence of the T makes it non-obvious.
I did look up "dropper" posts. Hadn't heard of those before.
I have a Trek 920 that people covet when I ride around. I replaced all the drive components a few years ago, since they were original from the early '90s. After it threw a chain and almost caused me serious injury I noticed hey, there's a bunch of teeth missing from these gears!
I learned a lot doing the overhaul... especially that you need a bunch of bike-specific tools!
I'm pretty sure my old Schwinn Continental is still in my parents' storage space, too...
QR is quick release (as in wheels)
BB is bottom bracket
Dropper post is an MTB thing and so are flat bars!