Enhanced Voicemail works the same way as Basic Voicemail. You have to dial in and follow a menu of commands to listen to each message. The difference is in the amount of messages and the length of time you can store them.
Basic Voicemail is a service that allows you to receive up to 3 messages each up to 3 minutes in length and you can save each one for up to 3 days.
Enhanced Voicemail is a service that allows you to receive up to 35 messages each up to 5 minutes in length and you can save each one for up to 10 days.
With Visual Voicemail each message is sent to your phone as an individual audio file. On your phone you see a list of messages identified with the name of the caller or just the phone number if the caller can't be identified. You tap on each message to listen to it and you can listen to them in any order you want and easily delete the ones you no longer want to keep.
Once you've used Visual Voicemail you will never want to go back to regular voicemail again.