According to Aquinas, Reason comprises of things that we know from what we have seen and what we think. From reason we know that God exists. Reason does not require a revelation from God for us to know.
Faith comprises of things that we know from God revelation to us. The revelation can be from the bible or what is being taught in the church. An example of faith is that we know that Jesus died for us so that we would have eternal life.
Faith cannot be known from reason alone but faith builds on what we know (i.e. reason). Hence Reason is subservient to faith.
Faith and truth are similar and there should be no difference between what faith and reason tells us.
