So IME: TLP has a huge impact on battery life by adjusting key tunables to enable power management, set power profiles, etc. In something like Windows these functions are built until the OS power management subsystem. On Linux, these userspace tools (of which there are a few) fill the same role.
Now, in Ubuntu, as you’ve indicated, they’ve incorporated power-profiles-daemon, which is another alternative to TLP. It’s entirely possible it does all the right things out-of-the-box! If someone were to run some experiments and report back, that’d be… pretty interesting… 