Syntax wise: Nim is to python what Crystal is to Ruby
Capability wise: both are incredibly powerful general purpose languages. Crystal is fully OOP, while Nim has a more functional/procedural bent.
Nim is better for DSLs and has a fascinating macro system.
For system language use, Nim is a better choice as you can use it with its Arc GC or no GC at all.
Perf wise, Crystal seems to be marginably faster in most benchmarks. Though at that level the difference isn't much.
crossplat wise, Crystal has no "official" windows support (and you cannot do webdev on it) while Nim has.
Ecosystem wide: Both are young languages and the ecosystems are tiny. Crystal has more and better options for webdev. Nim, IMO, is better for games, console apps etc.
Tooling wise; crystal IDE tools are far behind that of Nim. But both are terrible when you consider any decent language out there.
Ecosyt
Personally I like Crystal a lot due to its type system and syntax but you can't go wrong with either language.
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Syntax wise: Nim is to python what Crystal is to Ruby
Capability wise: both are incredibly powerful general purpose languages. Crystal is fully OOP, while Nim has a more functional/procedural bent. Nim is better for DSLs and has a fascinating macro system.
For system language use, Nim is a better choice as you can use it with its Arc GC or no GC at all.
Perf wise, Crystal seems to be marginably faster in most benchmarks. Though at that level the difference isn't much.
crossplat wise, Crystal has no "official" windows support (and you cannot do webdev on it) while Nim has.
Ecosystem wide: Both are young languages and the ecosystems are tiny. Crystal has more and better options for webdev. Nim, IMO, is better for games, console apps etc.
Tooling wise; crystal IDE tools are far behind that of Nim. But both are terrible when you consider any decent language out there.
Ecosyt
Personally I like Crystal a lot due to its type system and syntax but you can't go wrong with either language.