The RTM Requirement Traceability Matrix shows how requirements of different level connect to each other, e.g. how a top level customer requirement evolve via several abstraction levels to a specific low level requirement, e.g. a green button.
The Requirements Specification Document contains the requirements, e.g. The power button shall be green.
You'll find nice templates if you search for MIL STD 498 on Wikipedia.
An example to bring all together:
Top level requirement within an requirement specification document:
SSS0_1001: The system shall respect ISO xyz
Subsystem requirement within an other requirement specification document:
SSS1_1024: The power-on button shall be green.
RTM:
A matrix with level 0 requirements as columns, level 1 requirements as rows and "x" in the cells indicating which level 1 requirements realises which level 0 requirements.