When it comes to strength training, there is only one purpose to the workout: to increase the amount of force your muscles can produce to lift heavy objects. The size and shape of the muscles don't matter, provided they can exert maximum force when it comes time to lift.
Training for strength is usually done with low reps and high weight, and the training is aimed at teaching your central nervous system how to most efficiently recruit motor units when lifting. You lift with the goal of strengthening your muscles, reinforcing the joints, hardening the bones, and developing stronger connective tissue.
Unlike bodybuilders, the average strength trainee does NOT have a perfectly sculpted physique. They will usually have a higher body fat percentage, and their shape often tends to be blocky and solid rather than sleek and svelte. But when it comes time to use those muscles, they have much more functional strength and endurance than a bodybuilder.