Junior and Community colleges have many similarities, but there are also important things that differentiate them. Determining which option is best for you doesn't have to be that difficult if you know what you're looking for.
Junior Colleges are similar to four year universities insofar as they tend to give students the "full college experience." These colleges usually have dorms, food, sports, student activity centers, and many other things that you would expect to have at a four year school. These colleges also accept students from other communities, states, and even countries.
A typical junior college student is a recent high school graduate and many colleges have rules that limit the age someone can be if they want to live in the dormitories. That doesn't mean older students aren't allowed to enroll in these colleges though. Older students are often welcome to enroll in junior colleges, but they usually aren't allowed to live on campus.
One of the main differences between this and a community college is that most private junior colleges have an application process and you are not guaranteed admission.
Community Colleges are just that - colleges in a specific community. They typically offer associates degrees, but they also offer a wide variety of classes and sometimes trades depending on the location. Anyone can sign up for classes at a community college as long as you meet the educational requirements for the class.
People of all ages attend community colleges for any number of reasons. Some students are just out of high school and others are middle-aged people who are going back to school to further their career prospects.
So if you are looking for a full college experience but aren't yet ready for a four year university then looking into a junior college may be a good idea, but if you're a full time employee or single parent who is looking to take one class at a time then a community college might be your best route. It all depends on what type of educational experience you are seeking.