For starters don’t put yourself down; you are not clueless. Clueless people would not find a website and ask questions.
My second sentence merely points out that most residential tank water heaters will not make hot water as fast as it is being used. Some people don’t understand why their 5 gpm shower turns cold in 10 minutes.
EF is Energy Factor. It sort of relates to efficiency. Gas WHs have EFs of 0.55 to 0.8, electric WHs have EFs of 0.88 to 0.95, and heat pump WHs have EFs of 2.0 to 2.5.
Someone posted not long ago who had changed out the WH several times and finally found a hot water leak under the slab was his problem. If both your inlet and outlet pipes connect to the top of the WH, both lines should be about the same temperature (without heat traps) 30 minutes with no hot water usage. If the cold is still cold after 30 minutes it indicates you have flow through the WH.