Both Languages:
are strongly typed
are compiled languages and create native machine code
are mature languages and have extensive tools and support, both proprietary and open source
ported to many platforms
support complex data types, pointers and references, first class functions, and dynamic storage
use class style object orientation with inheritance and offer virtual and class methods
were derived from non-object oriented languages
Areas of difference:
Pascal was created as a language in which to learn structured programming.
C, the precursor to C++, was created to be a systems programming language.
C's language design and syntax is often described as atrocious. As an example, when defining Functions as passed parameters, describing the function parameters type correctly is difficult. It's not intuitive.
Pascal's syntax derives from the old standard Algol, C's is like hyper-FORTRAN.
Pascal allows for nested procedures and functions. C/C++ does not.
Pascal makes extensive use of a flexible type systems to define both complex data types and redefine existing types.
C++ uses a structure based system to define complex data types, and uses typedef's to redefine types.
C++ allows multiple-class inheritance. Pascal does not.
Pascal uses a Units structure with interface/implementation sections to allow modular programming. C++ uses header files and external reference definitions. The C++ system is messy compared to Pascal, and requires twice as many files for each module.
C and C++ have easier access to machine level features. The ability to work with signed and unsigned integers of varying size, access the bits within, and overlay structures on the same data are available in both languages. More work is required on the Pascal side, C being a systems language had that inheritance ability designed in.
C++ has a more flexible file input and output system based on function calls. Pascal's system is user friendly with more built in to the language, but is slightly challenged when accessing binary files.
C++ has a huge collection of libraries available, both standard to the language and externally available. Also enormous is the libraries contributed by enthusiasts.
Pascal also has a large collection. In addition, Pascal has access to virtually all C/C++ libraries through binding libraries.
C++ is an evolving language. Pascal is not. EC/ISO 7185 is the ISO standard for Pascal and has only one extension which does not reflect the Delphi extensions. C++ is EC/ISO14882 and has had five extensions with a sixth C++23 due out.