Alacritty is basically as minimal a terminal emulator as you're going to get, wezterm is the polar opposite end of the spectrum. Kitty is in the middle, the main thing that wezterm has that kitty doesn't that I'm aware of is the daemon process that allows you to disconnect/reconnect to sessions which is what allows wezterm to function as a tmux replacement (vs kitty can't replace that aspect of tmux). Compared to alacritty, it has multiplexing, ssh sessions (new tabs/panes opened in that session are opened in the context of the remote host without requiring additional authentication), incredibly flexible configuration via lua, etc. And as far as size goes, kitty and wezterm are written in different languages so comparing them directly is not so simple.