There is <1 Rads and +1 Rads. What is the difference?

<1 Rads means that the radiation level that hits you is below 1 Rad, (like very minimal to zero rads) depending on whether you are wearing rad protective gear or are on Rad-X etc.

< is the "less than" sign

Anything greater then 0. Not sure it can actually get to zero in an irradiated area even with equipment/drugs.

Edit: Anything greater then 0 but less then 1. I should have been more clear, sorry. hahahha

<1 rad = less than 1 rad per second

+1 (or more) = that positive amount of rads per second

No, 80% protection is probably still the maximum.

On topic, more than zero but less than one.