Operational : M ( P ) |= σ -> σ’
Denotational : M ( P ) |= κ -> P’
ie. In Operational semantics the meaning of a program is a transition function on a virtual machine, in Denotational semantics the meaning of a program is a mapping from an initial basis to a new (simplified) program.
http://etymon.blogspot.com/2007/09/operational-vs-denotational-semantics.html