OS Threads: + Simpler programming model - More resource intensive, so you usually need more user code to use them effectively Async + Less resource intensiv

OS Threads: + Simpler programming model - More resource intensive, so you usually need more user code to use them effectively Async + Less resource intensive, so you can have more of them and need less user code for management - More complex programming model Green threads: + Simplest programming model + Resource efficient - Requires a runtime