There are two possible locations for comparison that I can see:
https://gleam.run/frequently-asked-questions/#Elixir Here’s a non-exhaustive list of differences:
    Elixir is gradually typed, while Gleam is fully statically typed.
    Elixir's type system does not have generics, while Gleam's type system does.
    Elixir has a powerful macro system, Gleam has no metaprogramming features.
    Elixir’s compiler is written in Erlang and Elixir, Gleam’s is written in Rust.
    Gleam has a more traditional C family style syntax.
    Elixir has a namespace for module functions and another for variables, Gleam has one unified namespace (so there’s no special fun.() syntax).
    Gleam standard library is distributed as Hex packages, which makes interoperability with other BEAM languages easier.
    Elixir is a larger language, featuring numerous language features not present in Gleam.
    Elixir has an official test framework with excellent support for concurrency, partitioning, parameterized tests, integrated error reports, and more. Gleam has no official test framework, but there are multiple community-maintained frameworks.
    Both languages compile to Erlang but Elixir compiles to Erlang abstract format, while Gleam compiles to Erlang source. Gleam can also compile to JavaScript.
    Elixir has superior BEAM runtime integration, featuring accurate stack traces and full support for tools such as code coverage, profiling, and more. Gleam’s support is much weaker due to going via Erlang source, resulting in less accurate line numbers with these tools.
    Elixir and Gleam both use Erlang's OTP framework. Both have additional modules for working with OTP, which provide APIs more in the style of each respective language. Both common use Erlang's OTP APIs directly, but Elixir can do so more conveniently and concisely due to having a less-strict type system.
    Elixir currently has superior deployment tooling, including support for OTP releases and OTP umbrella applications.
    Gleam’s editor tooling is superior due to having a more mature official language server, but Elixir has recently announced an official language server project which is in active development.
    Elixir is more mature than Gleam and has a much larger ecosystem.
    Gleam and Elixir compile at similar speeds due to using the Erlang compiler as their compiler backend. Elixir's macros are evaluated at compile time, so a program that uses macros will take longer to compile the larger the amount of work performed in macros. Gleam has no language features that result in slower compilation.
https://gleam.run/cheatsheets/gleam-for-elixir-users/ This has to much content to reproduce.