I would like to say that there is no difference among these terms except connotation.

In a simplest way,

Fatigue strength is the highest strength that a material can withstand without failure.

Fatigue limit is that limit at which material fail.

Endurance limit is that point after which a material can't go back rather than there is a lost of stamina and metal goes to fail after that. 

So, everything denotes exactly the same point but in different ways.