To me…
Emunah is just the general belief that there is a HaSh-m who created the universe and gave us the Torah.
Bitachon is much harder. Bitachon is the ability to maintain your emunah when things seem bad, even very bad, even terrible. As “yungerman1” (above) said, to trust that HaSh-m is there with you and that He does only what is good, even if we can’t see how it is good now. To trust that even when we have crushing financial issues, or health issues, or loss of a loved one issues, and that eventhough right now, with our limited perspective, these things seem horrible beyond horrible, to know that nevertheless, despite how these things seem to us now, that in HaSh-m’s great master plan, even these “terrible” things are ultimately good.
Sometimes we will realize these “terrible” things were good in just a few months time. Sometimes in a few years time. Sometimes we may not see how it was good until at 120 we go “upstairs” and can see that bigger picture.
BUT… bitachon means that though we do not understand NOW how what seems bad IS good, we still, internally, DO trust that it is.