Terra programs are kind of embedded in Lua, you can't separate the two. So to be very precise: Terra has metaprogramming done via Lua at compile-time, with Terra types being Lua values you can pass around, transform, return etc. in the metaprogramming "layer" of the Terra program.

In Zig, you do the metaprogramming in Zig itself, but you're also limited somewhat as you can only use the comptime "layer" of the program. In my mind, it's very similar.