I've noticed that I could run on the treadmill at a faster pace for about 40 minutes but When I run outside not uphill or anything I could barely run for 2 minutes without before being out of breath and needing to stop. It is pretty warm at the gym it is also outside but i run early in the morning so it's not that hot outside so What is the difference ?
The treadmill does a lot of the work for you. You notice you can't just stop running on one or you faceplant? Yeah, that's why.
It's a lot easier for me to run on a treadmill too. I tend to try to run too fast outside so I really have to focus on running slower at first and then I'm able to keep a better pace.
It's like how walking up an escalator is easier than walking up stairs. The ground is moving for you, so you're not doing as much work. When you walk normally there's a natural gravity resistance.