In the past these two had very little in common, however I thought I’d briefly compare as they are increasingly used together and becoming quite similar in places.
One of the biggest differences in the two is that c# relies on threading to support concurrency whereas node js does not, although threads are used under the hood.
One of the biggest challenges I encountered recently was with array / collection mapping and filtering. Linq is the way to do it in C# whereas js gives you a few different options – lodash is what is used in my place of work. They are similar but a little different. I won’t go into detail here.
There are many more similarities and differences these are but a few….