There many important dimensions of difference in programming languages that matter to the programmer. Which of those are "fundamental"? What does that question even mean??
One fork in the road between academic/theory answers to that question and developer answers concerns the role of the standard libraries and available IDEs. The out-of-the-box work/contribution of those tools is super important to developers in practice, but irrelevant to academic discussions. Some academics focus on real theory and declare that their statements about PL are basically a kind of applied mathematics - use it if it is somehow relevant to you, and ignore it, like other piles of math, if it isn't. Others make claims that the distinctions capture important properties like preventing careless errors. In that case, one can also talk about which tools are helpful/important to prevent careless errors. And similar remarks can be made for other properties such as speed/brevity of coding/expression, availability of pre-existing parts and ease of integrating them, etc. IMO, there is room for theory that tries harder to abstract the dimensions that drive software practice.
One fork in the road between academic/theory answers to that question and developer answers concerns the role of the standard libraries and available IDEs. The out-of-the-box work/contribution of those tools is super important to developers in practice, but irrelevant to academic discussions. Some academics focus on real theory and declare that their statements about PL are basically a kind of applied mathematics - use it if it is somehow relevant to you, and ignore it, like other piles of math, if it isn't. Others make claims that the distinctions capture important properties like preventing careless errors. In that case, one can also talk about which tools are helpful/important to prevent careless errors. And similar remarks can be made for other properties such as speed/brevity of coding/expression, availability of pre-existing parts and ease of integrating them, etc. IMO, there is room for theory that tries harder to abstract the dimensions that drive software practice.