I notice that if you get two people to workout one will usually tend to get sore, overwork, or have a great deal of pain the next day while another will get a good workout and succeed.
And this is not experience based either because I know some who have worked out years and get sore if a little overworked, and some who never workout who do not get sore as easily.
Delayed onset muscle soreness, the type of muscle soreness you get from a workout, is not an indicator of anything other than your body not being used to what you just did.
If two people train together and one gets soreness and the other doesn't it just means the other person is adjusted to that routine already. It's not a negative at all and the person who is sore is not getting any extra benefit from the workout.
It sounds like the question you're asking is really sidestepping the question you want to ask, due to you implying that the person who doesn't get sore "will get a good workout and succeed." This is not the case. Getting sore is nothing other than your body not being adjusted to something, and a sore body can still continue working out.
The simple answer is that everyone is different, and every day is different, and each gym session is different. Some days I might be on my game, other days I might have a terrible workout - even if all other factors appear the same.
It might be the effect of a workout earlier in the week, or a bad sleep, or slight dehydration or any number of other things.
And as Kasra said, sore is not a measure of a workout - it may be connected but is often orthogonal to your workout success.
What is wrong is expecting consistency - we are humans. We vary. That's life :-)
