If OL had come out first, I don't think there would be the same house name attached to both series. They probably would not be in the same "Axlerverse" either.
I would think Mark might have had more of his vision of how he wanted OL to go from the start. One example comes to mind the Cerberus crew would have had their base of operations in Area 51 or some such place like that, and also the mat trans chambers and some other things related to the DL universe would not have been in the series.
If DL came out some years after OL, I think it would have been more likely to be a series unrelated to OL. Unless Mark was involved in the creation process of it and even wrote some to start it off then maybe it could have been some kind of spin-off of sorts, but most likely I would say DL would have been separate from OL and there would not be any comparisons between the two.