Whats the difference - Money Market fund like SPRXX or CDs?

One of the main differences that steered me away from SPRXX was when I read the fine print I found that it is not FDIC protected and neither is FDRXX, I think I remember the Fidelity site saying they are not FDIC insured nor insured by any other government backed failure program, I don’t know if they may possibly be backed by SIPC which is a non-government protection program.
Their core or Sweep account is insured to $250,000 but it doesn’t pay as much interest. I’ve recently picked up some CD’s because of the improved interest rate payout and the are FDIC backed. In the current political environment, I’m not willing to chance any of my retirement account to funds that aren’t backed by FDIC.