Everything about memory

During a recent Rust Q&A Session on my twitch channel, someone asked a question that seemed simple: why are small string types, like SmartString or SmolStr, the same size as String, but small vec types, like SmallVec, are larger than Vec?

It feels like an eternity since I've started using Rust, and yet I remember vividly what it felt like to bang my head against the borrow checker for the first few times.