1-ans) Simscape is a part of Simulink. As you know Simulink is a graphical
programming Environment for modelling , simulating and analysis of
Dynamic Systems.Where simscape is a Physical modelling part in simulink environment.Like hydrauliks, Electrical & Mechanical.
2-ans) All in Matlab Programming Language.
3-ans)Both uses Modelling Blocks, as simscape is a part of Simulink No such major difference, bt There is a source code provided for each block in simscape , you can make changes in that code to make your own custom block also in simscape there is a language called Simscape programming language to design new custom blocks.
4-ans)By Simscape Programming language you can design new blocks by writing codes in matlab programming language.
(
https://in.mathworks.com/help/physmod/simscape/lang/what-is-the-simscape-language.html)
5-ans)Blocks are converted to source code than to machine code by matlab compiler.