Non exaustive list:

- proper strings with bounds checking

- proper arrays with bounds checking

- no pointer decays, you need to be explicit about getting pointers to arrays

- less use cases of implicit conversions, requires more typecasts

- reference parameters reduce the need of pointers

- variant records directly support tags

- enumerations are stronger typed without implicit conversions

- modules with better control what gets exposed

- range types

- set types

- arenas

There was plenty of Pascal code on Mac OS including a Smalltalk like OOP framework, until C++ took over Object Pascal's role at Apple, which again it isn't C.

I love the "but it has used Assembly!" usual rebutal, as if OSes written in C weren't full of Assembly, or inline Assembly and language extensions that certainly aren't C (ISO C proper) either.

If you prefer, Zig is a modern taken on what Modula-2 in 1978, and Object Pascal in the 1980's already offered, with the addition of nullable types and comptime as key differentor in 40 years, packaged in a more appealing syntax for current generations.