An annual license is just that – you can use it for one year. During the subscription period, you will receive both minor and major upgrades.
A lifetime license means you can use the purchased program for as long as you wish. The current version of the program will be available for an unlimited amount of time. For this version of the program, you will be provided with free minor updates (i.e. versions 21.1, 21.2 and so on). However, major upgrades (versions 21, 22, 23, etc.) have to be purchased separately.