I don't understand free-tier!??

Questions / Help
3

Is
2,340 hours per month of shared cpu 1x time same in following cases?

  1. Run 3 shared-cpu-1x VMs with 256MB RAM full time.

  2. one 512MB RAM and one 256MB RAM full time?

if yes, does it mean that I can run one instance of 512MB RAM and one instance of 256MB ram under free tier?