What's the difference between parenthesis $() and curly bracket ${} syntax in Makefile?

Question

Is there any differences in invoking variables with syntax ${var} and $(var)? For instance, in the way the variable will be expanded or anything?

Answer 1

As already correctly pointed out, there is no difference but be be wary not to mix the two kind of delimiters as it can lead to cryptic errors like in the GNU make example by unomadh.

From the GNU make manual on the Function Call Syntax (emphasis mine):

[…] If the arguments themselves contain other function calls or variable references, it is wisest to use the same kind of delimiters for all the references; write $(subst a,b,$(x)), not $(subst a,b,${x}). This is because it is clearer, and because only one type of delimiter is matched to find the end of the reference.