An oasis is an area or spot in the desert that has water in it and is able to support vegetation. On the other hand, a desert is a region that is large, hot, dry, barren and often covered with sand or rocks. It has little or no rainfall, for this reason, there is little or no vegetation.
The desert environment is a very unpleasant one, especially with its hotness and dryness. In other words, an oasis in a desert offers a quench to thirst. In real life circumstances, an oasis offers refuge, sustenance, safety, peace, and support.
There are times people go through what might look like a desert in their lives, however, it is important to remember that there is an oasis in a desert. You have to hang in there and be patient enough to get to your oasis.