The Strength Curve refers to the ability of a muscle to generate force at different lengths. Muscles are strongest in the mid range (not full shortened or fully lengthened) but the relative degree to how much more force they can produce varies by muscle, due to their structure (referred to as architecture) and the mechanics of the joint(s) they act on.
The Resistance Profile is a description of where a particular exercise is relatively the most challenging throughout the range of motion.