You are talking about two different types of cap rates. One applies to the income stream generated by the payments made on the ground lease. The other applies to the income from the improvements (building).
I have worked on many a ground lease transaction both from the side of the ground lessor and the ground leasee. The transaction can be very complicated and must consider many factors like the lease rates, comparison to market lease rates, credit worthiness of tenant(s), market value of the improvements (if any), reversion on the lease, term of the lease, etc. etc.
Jan 5, 2009