Treadmill to track

I’ve been running on a treadmill for quite sometime now and just switched to a outdoor track. I run out of breath significantly sooner then I did indoors. Clearly the track surface is harder then the treadmill…

Is the harder surface having an impact on my running distance or is it just in my head?

This past winter created difficult conditions outdoors and our apartment complex installed a treadmill and other exercise gear. I used the treadmill for most of the winter. When winter was over I returned to running outdoors on roads. Running was much more difficult from March to June. Three weeks ago in the middle of a 5K race on a trail I realized that my gait had changed on the treadmill. I have been working to get my old gait back and running is much easier. On the 4th of July I ran my fastest 5K since 11 years ago.