Being a mature student is neither easier nor harder than being a youthful one. It's just different. Doubts about being able to understand lectures, write essays and make friends are common to all students, but matures tend to be more open about their insecurities.
It's never easy starting college as a mature student. Young students usually have friends from school to hang around with and matures often feel lonely and conspicuous to begin with. But this quickly passes as they make friends. Matures tend to gravitate towards each other, but young students are quite happy to befriend matures if they're given the chance. Just make sure you don't end up as the class Agony Aunt/Uncle.
The good news is that mature students have a number of advantages over their younger classmates. For a start they have made the decision to go to college because they want to so they tend to be focused, committed and quite happy to read and study. They are unlikely to be distracted by the lure of the bar or the social scene and they tend to handle essay deadlines and exam stress better than younger students.
The downside of being an older learner is that it takes longer to absorb information. But don't worry, that's perfectly normal. One of the ways of making life easier is by finding like-minded people with whom you can study and exchange notes and information. Groups of up to six can work quite well. Any bigger and they get unwieldy.
If you're returning to study after a long break you need to make things as easy for yourself as possible. Start by finding a quiet place where you can work and leave your books and papers undisturbed. Then try to get into a study routine. Start off with an hour or two and work up. If you are assigned a mentor or tutor take advantage of the system and let him or her help you. Invest time in getting to know your way around the library and if your college offers a study skills course do it. Finally, if you don't understand something, ask. Lecturers are usually quite happy to answer questions privately.