I think it goes without saying that the more muscle a person has, the stronger he or she becomes. Not in relation to everyone else, necessarily, but in relation to how they themselves were before they put the muscle on.
And, while bodybuilding is, technically, strength training – primarily it’s not for strength, but purely for cosmetic reasons. Strength training, on the other hand, is not for cosmetic reasons but simply for brute strength.
While there is certainly some crossover between the two types of training – bodybuilding yields more strength and strength training yields more muscle – they really are two very different beasts, and the outcomes very different.
That’s why many people like to utilize a combination of the two.
Building muscle mass in the bodybuilding context is the quickest and most efficient way to ‘get big’, as it were. It relies on higher rep ranges (7 – 15) and lower weight. Bodybuilding training primarily targets the slow twitch muscle fibres, of which the average persons muscles are predominantly made up of.
Strength training is different again. It uses lower rep ranges (1 – 5) and heavier weight. This tends to hit the explosive, fast-twitch muscle fibres, of which our bodies have less of. This is one reason why those who lift for strength seldom attain the kind of physical muscle size that those who train as bodybuilders do. Yet, those who train as bodybuilders – for their size – can not generate the kind of raw power that those who train for strength do.
When all is said and done, for each of the weight training practices, the unbreakable universal laws of eating sufficient nutrients (calorie surplus) and sufficient rest are still the difference between making progress and not.