Some difference off the top of my head:
- Nim so far has been a GC-ed language (I know manual allocation is possible, and an ownership system is planned, but this was the default for most code so far). Lobster has been reference counted (and now compile time reference counted) from the start. Nims proposed ownership system is pretty cool, but still requires a fair bit of programmer cooperation, in that sense it will sit somewhere between Rust and Lobster in terms of programmer friendlyness.
- Lobster has a type inference algorithm that is able to go further than most languages in terms of allowing code without types to "just work". Nim has nothing even remotely like this.
- Nim is faster. Nim was designed for near native speeds from the start, Lobster started life a very high level language that slowly become more low level. There's nothing that prevents Lobster being as fast as Nim, it just will take a bit more time.
- Nim is more mature, in the sense that it has been around longer, has more libraries and tooling etc, and a larger community.
- Lobster has great support for programming with higher order functions: terse syntax, best possible type inference, zero overhead (compared to manual loops), non-local returns etc.
So in summary I'd choose Lobster over Nim if you care about Lobsters type and memory management or higher order function features, or if you like the idea of a language that makes games/graphics out of the box easier. If you just want to "get the job done", Nim probably is ahead of Lobster at the moment :)
