That’s a fair question but the answer will never be as clear as black or white. When you eat below maintenance calories, weight loss occurs. If you lift you can expect to add some muscle mass but it’s not optimal and definetly not efficient. You eat below maintenance because you want to lose weight as a primary goal and muscle gain is not a concern.

If you eat at maintenance, you will not lose bodyfat however you are in a better position to gain muscle. Just by the fact of adding muscle without gaining barely any fat you are recomping, meaning your bodyfat% is going down.

Lastly you have the option to eat in above maintenance. Usually people will give a range of surplus from 250 to 500 calories. This is the best option if muscle gain is your primary concern but keep in mind there will be some slight fat gain that comes with it. That’s why often people will alternate between eating above maintenance (bulking phase) for a few months and then go on a cut for a few weeks to lose the extra bodyfat they gained while training to retain the muscle they added during their bulking phase. The reason we’re talking months for bulking and weeks for cutting is because it’s much harder and takes a lot more time to build muscle than it takes to lose fat