Unless I'm wrong (possible), there are now only 3 levels of license available. Technician, General and Extra. No code is required now. A sad thing in my opinion. Code is still used by some and is a mode that will punch through interference and noise. The extra class is the most technically demanding license. A good source of info is arrl.org.
Each class has some amount of electronics with a smattering of rules/regs, procedures, practices, etc. From tech to extra, each gets a little tougher. In the extra class it gets into satellite communication modes. Took that test once and didn't fare too well. May try again sometime. Currently I hold a now extinct license, the advanced class.
73 (best regards)
Owens / N5QNS
I am studying for the Tech license off and on as time allows. I have an older Army Jeep I am am outfitting with Military radios now. I want to be in compliance with FCC rules and don't plan to key up, or even have a working setup, until after I pass the testing and get my license, Later, prob some kind of handheld commercial unit. Still learning the very basics.