Speculating AF here - PCA - Permanent Change of Assignment. This is a reference that differentiates a PCA with and without a PCS.
http://static.e-publishing.af.mil/production/1/af_a1/publication/afi36-2110/afi36-2110.pdf
For the Army you can have a PCA without a PCS if you change major command unit of assignment but are not physically moving outside the local area .... Hospital assignment to BDE surgeon assignment with no PCS as they are within x distance.
Usually the term is in used in conjunction - with or without a PCS.
Call your gaining command for clarification as to their expected reporting date.
Edit: Psychbender beat me to it in simpler terms