Well, Rust's standard library has three components, named core, alloc and std
The no_std Rust only has core but this is indeed a library of code, and freestanding C does not provide such a thing = freestanding C stdlib provides no functions, just type definitions and other stuff which evaporates when compiled.
Two concrete examples to be going along with: Suppose we have a mutable foo, it's maybe foo: [i32; 40]; (forty 32-bit signed integers) or in C maybe they're int foo[40];.
In freestanding C that's fine, but we're not provided with any library code to do anything with foo, we can use the core language features to write it outselves, but nothing is provided.
Rust will happily foo.sort_unstable(); this is a fast custom in-place sort, roughly a modern form of introspective sort written for Rust by its creators and because it's in core, that code just goes into your resulting embedded firmware or whatever.
Now, suppose we want to perform a filter-map operation over that array. In C once again you're left to figure out how to write that in C, in Rust foo impl IntoIterator so you can use all the nice iterator features, the algorithms just get baked into your firmware during compilation.
The no_std Rust only has core but this is indeed a library of code, and freestanding C does not provide such a thing = freestanding C stdlib provides no functions, just type definitions and other stuff which evaporates when compiled.
Two concrete examples to be going along with: Suppose we have a mutable foo, it's maybe foo: [i32; 40]; (forty 32-bit signed integers) or in C maybe they're int foo[40];.
In freestanding C that's fine, but we're not provided with any library code to do anything with foo, we can use the core language features to write it outselves, but nothing is provided.
Rust will happily foo.sort_unstable(); this is a fast custom in-place sort, roughly a modern form of introspective sort written for Rust by its creators and because it's in core, that code just goes into your resulting embedded firmware or whatever.
Now, suppose we want to perform a filter-map operation over that array. In C once again you're left to figure out how to write that in C, in Rust foo impl IntoIterator so you can use all the nice iterator features, the algorithms just get baked into your firmware during compilation.