I'm not sure if there's any research that differentiates between the two.
The one difference you see with someone on exogenous test is that they don't have the regular swings that endogenous production has. It won't decline post training, it won't be lower in the evening (granted proper injection frequency/ester).
I'm not sure how different it would be; it's not like exogenous GH and endogenous GH with all it's different isoforms. Maybe some of the smarter residents of PM can chime in.
Muscle growth is more than just testosterone levels, that's one thing to take into consideration. I've had 1100+ ngl test levels as a natural, but I graduated high school at a 128 lbs, and didn't really start putting on muscle until training, and diet were properly dialed in.
Just a few things to consider.