Community colleges have lower wages for their permanent faculty compared to universities and 4 year colleges. Community colleges usually have very little in terms of athletics. Athletics at most universities are a huge sink in terms of expenses. Very few universities generate enough money to pay for their athletic departments and none of them as far as I know generate enough money to pay for the buildings and stadiums they use. Community colleges mostly focus on teaching classes and lack the accoutrements that universities generally have.

On average, they must be less wasteful simply because their tuition is so much lower. There's lower margins so less room for waste. They are also not a luxury good (college is) so they are more subject to market pressures.