Sure, one can say that “tennis is tennis”, but that isn’t a very accurate axiom as playing outdoors can be far different than playing indoors (especially in the comfortable confines of our wonderful tennis center).
It is even more important in outdoor settings to pace your energy and stay hydrated, as fatigue can become even more of a factor than it normally would. As the temperature rises, so does the importance of mastering the art of energy reservation and hydration. Even if you do not feel thirsty, get something to drink every opportunity that you have. You do not want to get caught in the middle of a long game (or pair of games) before a turnover being thirsty because it could end up costing you.
Another essential part of playing outdoors is simply knowing your environment. The court can get hot and there is less uniformity to outdoor courts than there is for indoor courts. Some are going to play far faster than other and some are going to be affected by wind more than others. Be cognizant of this and prepare accordingly. In strong winds you should tailor your game a bit differently in general and especially depending on which direction of the wind you are facing. This could be the difference between victory and defeat in a close match.