One is growing and the other is not.
One has planes on order the other does not.
One treats people with respect, the other treats people with contempt.
One believes in paying people what they earned, the other resents every penny it pays its pilots because pilots should work for free, after all they are working their way to the majors.
One has experienced, intelligent management, the other "takes his marching orders".
One has standups that pay well, one day trips, 2 day trips, 3, and 4 day trips, the other has standups that pay 2/3 what the other pays and 4 day trips.
One you can drop and add trips, the other you might be able to make a trade once a year.
One has an HR department that knows what it is doing, the other just fires anyone who has a problem.
One allows you vacation, the other one takes pride in cheating you out of it.
One allows you to jumpseat home after your last trip, the other cuts your CASS first and makes you buy a ticket home, and they suggest you make it a train ticket.
Both have good guys working there.
One has 4.2 per day minimum, one has 4 but only if you start before noon and finish after 5pm so a 4 day trip has a guarantee of 10 hours at times.
One has many bases and is about to move into the East Coast big time, the other has several small bases.
One is getting another 50 ERJ-175s in the next 6 months, the other is trying to make guys think they are getting some.
One has an effective non-union, the other has a union with no power.

It took me about 10 minutes to go through the posts and make the list. I stayed away from the more contentious ones. How did I do? You can research which is on each side of the list.