I have read Strongholds & Followers, but haven't reviewed it. It's been a long enough time that I don't remember the rules off-hand. so I can't make a detailed comparison at the time.
But as a skim-through comparison...
S&F is much more detailed for creating PC dwellings, rather than being a single chapter. It's much more useful if base-building and domain management is a major part of your game.
S&F is also more expensive during the initial purchases. Even the most meager Strongholds run into the thousands of GP just to buy, and much more when upgrading them. Additionally the time progression in S&F (for building and upgrading) is measured in explicit days, while for A Life Well Lived Downtime Periods are the major time unit. As a Downtime Period is about 3 weeks and there are no explicit details for building a Base from scratch (the only real prerequisite is buying it with gold or obtaining it as a reward) it's more suitable for campaigns where the PCs may not be sitting around for years between adventures and progression.
The main bonuses Bases provide are in the form of Features and Rooms, usually simple things like advantage on certain tests, regaining more Hit Dice during a Long Rest, gaining free or bonus uses of consumable equipment, and the like. Nifty little things, but no big game-changers in terms of balance. S&F can really up the personal power of PCs, such as granting them lair actions while in the same hex/province as their Stronghold, gaining NPC retainers, and blatant improvement to core class features. Additionally, individual Strongholds are strongly tied to class and theme, while a Base can easily be multi-purpose for various PC roles and abilities based on the Rooms and Features.