Hare is much simpler than Zig and has a much different design, things like Zig's comptime is absent in Hare. Hare also has, in my opinion, a more fleshed out standard library than Zig. However, they don't compete in some respects: Zig targets nonfree platforms like Windows and macOS, and being based on LLVM gives Zig a greater range of platforms/architectures OOTB.
Andrew might be able to expand on this.