Javap is just an "informal" dis-assembler, its output gives you information about the bytecode, but is not suitable for it to be used by an "assembler", it is rather for it to be read by a human.
The traditional difference (from the C language world):
- Compiler: compiles a relatively high-level source code to assembly language
- Assembler: compiles assembly code to machine code
take your conclusions for "de-compiler" and "dis-assembler"
Sometimes a software that does both steps (disassemble and decompile) is also called a decompiler, but it still depends on the context
