Stress tolerance is what Stanford University stress expert Robert Sapolsky refers to as your stress signature. Everyone has different sensitivity levels to stress. There are certain areas of the brain that have receptors for stress chemicals, and counter-intuitively, the more receptors you have in these areas the less sensitive you are to stress. To put it another way, someone with a lot of receptors in this area is going to have a high tolerance for stress.
Stress resistance is a term that is used by Johns Hopkins stress expert, Dr. George Everly, to describe a person who isn't bothered by stress at all. This person just let's stress roll right off his or her back. It's almost like an immunity to stress. And just like a real vaccination some people cultivate this state of immunity by deliberately exposing themselves to controlled doses of stress. Adult drivers all go through this very same process when they first learn how to drive. We start out terrified by it (for good reason) and eventually get to the point where it isn't stressful at all.
Stress resistance could be learned in this same way with everything from handling snakes to sky-diving. Most of us choose not to, or never believe we could get to the point where stressful activities lose their power to stress us out. I've seen Dr. Everly speak on several occasions, and he likes to show this video to illustrate stress resistance. It clearly shows what it's like NOT be the least bit bothered by what would crush others.
Resiliency is defined as bouncing back from adversity. Everyone deals with adversity differently. Some people are slayed by it. Others take a long time to recover from it and still others jump right back into the ring and start fighting again. Focusing on the time it takes you to recover from a fall (which in this case means ANY kind of adversity) is a good way to define your own sense of resilience.
A common metaphor for all these concepts is derived from weight training. When you do some weight training for the very first time, the next day your muscles are sore. This soreness is the result of very slight tears that take place in the muscle fiber. If you give those muscles time to properly heal and recover, (i.e., a few days of rest) they grow back even stronger than they were before. We deliberately stress the muscles in order to make them stronger.
We can apply this same approach to life every time we remind ourselves that by facing stress head on, it makes us stronger. And this of course is reminiscent of German philosopher's Friedrich Nietzsche's famous quote: "Whatever doesn't kill you makes you stronger."
So resilience and stress resistance can be cultivated and or learned. Even stress tolerance can be enhanced through changes in the brain that take place as the result of neuro-plasticity. The brain changes in response to experience, so if you change your attitude toward stress and see every stressful situation you encounter as a "learning opportunity" the areas of the brain that help you modify and control stress are going to change as well.