Yes, and under the hood Handbrake is using the FFmpeg libraries. Handbrake's value is providing simple presets that "just work" for converting video for various uses. Want to convert video for playback on an iPhone? Handbrake has you covered.

Yes, but Handbrake provides a GUI. Ffmpeg is fantastic, and I believe supports a wider range of formats than Handbrake, so it's the power user's tool of choice. But Handbrake is way more accessible for the average user, and is very high quality in its own way.

Aside from the interface, Handbrake provides many features not implemented in ffmpeg, especially concerning extracting data from DVDs.

Handbrake is also the easiest way for non-technical people to transcode videos from one format, resolution, or quality to another.

I find ffmpeg more intuitive. Handbrake only has presets, and it pre-fills so many options for you. Why can't I just have "original" everything, just change the format? I don't want any changes except codec, but with Handbrake I don't feel confident it's not going beyond that.

brb reading man pages. again. in three different terminals.

ffmpeg is a great tool, and time is well spent getting to know how to use it. but it takes a lot of time/effort to get there.

Well, yeah, both can be used for mostly the same things (probably ffmpeg has more features in total though), but ffmpeg doesn't have a GUI, which HandBrake does.