The term hypothesis is used to describe the explanation of a particular occurrence. The hypothesis can occur from a mere guess of a particular situation or a typical description or propositions made from one or more things that occur. It is being defined somewhere as the antecedent of a conditional statement.
This term is generally used in the scientific process to define a phenomenon that can still be further investigated or experimented with. However, it is necessary to provide well-defined details when presenting a hypothesis. On the other hand, the term theory is more used in the world of science than any other.
The way this term is used many times is also synonymous with the hypothesis. Theory can be used to refer to just simple guessing or to explain some occurrences too. A theory can be arrived at by testing hypotheses, and carrying out more experiments. As far as a theory has not been disproved, it remains valid.