iota.rs, wallet.rs and identity.rs
Code's organization: How are IOTA's libraries structured?
In order to better analyze the code, I recommend downloading the latest version of the source code (either by downloading and extracting the zip file or using git clone) and opening it in your IDE.
iota.rs
The main package of this workspace is located in the client/
directory. This package will be built as a crate with the name "iota-client" (use this name to search for it in https://crates.io).

Project Structure of iota.rs
A look at client/Cargo.toml
reveals the features of the library crate.

Features of iota-client
If you're looking for another entry point into iota.rs, you can check out the chapter titled Simple App -> Core API and iota.rs. This chapter provides more information about the structure of the iota-client using an example.
wallet.rs
There is no workspace but only a package which will be built as a crate with the name "iota-wallet" (use this name to search for it in https://crates.io).
A look at Cargo.toml
reveals the features of the library crate.

Structure of wallet.rs and features of iota-wallet
identity.rs
The main package of this workspace is located in the identity_iota/
directory. This package will be built as a crate with the name "identity_iota" (use this name to search for it in https://crates.io). The other packages of this workspace are dependencies of the main package.

Project Structure of identity.rs
A look at identity_iota/Cargo.toml
reveals the features of the library crate.

Features of identity_iota