From the outside looking in, I see 3 major differences.
Firstly, our European colleagues tend to be more secretive about contracts. Not sure why this is so. It’s pretty easy to get the contract of any carrier in the US. That contract will spell out pay and work rules for all the pilots at that airline.
Secondly, all pilots work under the same contract. It doesn’t matter if you’ve been with the company for 3 months or 30 years. The same work rules, pay rates and retirement provisions apply. A rising tide lifts all boats.
Thirdly, the 1500hr ATP rule not only increased safety, but put a stop to people with 250hrs flying part 121. In Europe, I gather that 250 hrs gets you into a Boeing or Airbus. It probably doesn’t hurt to get some experience before becoming a student pilot in an A320. By the time you have 1500 hrs, you’re probably less likely to be willing to work for peanuts.