This will probably get me flamed, bashed, slammed or whatever you call it, but here goes anyway.
1) All regional airlines are definetily NOT the same. Putting them in one basket is an oxymoron. Some are identical to a major airline in terms of how they train, standards they maintain, what they do and who they hire. Others are scheduled operations, but any resemblance to an airline is imaginary. Most are in between the extremes.
2) There are several so called regional airlines on which I don't allow my family to fly (and it's not because they are small either). Some of these are among what I call the "imaginary" category and they do fly "jets".
3) Except for the fact that both fly airplanes, there is little comparison if any between a "real" scheduled airline and a non-sched 135 operation. Different worlds.
4) Most freight operations (excepting FDX, UPS & DHL) are fly-by night (and I'm not refering to their hours of operation). YIP is full of them, operating heavy equipment. (Zantop used to be OK, don't know now.)
Most pilots can adapt to a real airline's routines regardless of where he/she got the flying experience. If you have the sheep skin required, the flight hours required, and are lucky enough to get an interview, you'll get hired sooner or later. Your "attitude" as perceived by the HR people, on that day, and a lot of luck does it.
There is no magic formula for getting hired and the so-called standard is not standard at all. Who you know is often more important than what you know. Some very big airlines never test your flying skills before they hire you, others think your performance in a sim you've never flown before is a big deal.
It is virtually impossible to determine who is a "good pilot" and who is not in an airline interview. If you can fill the squares that company wants on that day and the interviewers "like you", you get the job. Thousands of highly qualified and very competent pilots never even get an interview at a major airline let alone a job. You don't get hired because you "paid your dues". You get hired if you're lucky.
I fly for a regional today. I got the job becaue I was in the right place at the right time. I've flown for more than one "major" in more than one place in more than one "big jet" and I got those jobs for the very same reason. It's the luck of the draw.
The military background (as a pilot) helps (and yes, I'm an x-military pilot). IMO there are three reasons for that, 1) you meet a profile that HR people have decided they like; 2) military pilots network; 3) when pilots are involved in conducting the interview process (at a major) 70 - 80% are former military pilots and they favor their own. At one major airline, if you're a Naval Aviator, your chances are much higher than if you happen to be Air Force. In general, the majors don't like Army pilots. Why? Because most are Warrants not Officers. None of it has anything to do with flying, it's a club.
The process is far from scientific. If you want the job, network, network, network as much as you can; have a 4-year degree (even if its under-water basket-weaving); get the numbers right in your logbook; dress nice and look polished, shine your shoes, cut your hair and pick the right necktie; speak correctly; know a little about flying in general; consider yourself lucky if you're a female or a minority; CARRY YOUR GOOD LUCK CHARM!
Good luck and best wishes in your effort.
PS. Some "regionals" will hire any warm body. Others are just as picky as a major, but require less hours in your log book. Still others will let you buy the job (I'd stay away from those), even if you have difficulty speaking in English and yes, I think there is a BIG difference between buying the job and completing some required training BEFORE you're hired.