The following features are provided in the Bourne shell and Bash but not in Plash.
Environment variables. Plash doesn't provide any way to set environment variables, and it doesn't perform any substitution of environment variables in arguments.
Loops and conditionals. "if" and "while" and "for ... in" are not provided. Shell functions are not provided.
The "&&" and "||" operators.
Here-documents (ie. redirecting input using something like "<<EOF").