Complex sentence: CFZM offers instrumentals (in the form of a Sunday evening 3 hour big band segment) which WECK does not and many specialized music programming blocks while the only specialized music block WECK has is a weekly 3 hour polka music show.
Split into simpler sentences: CFZM offers instrumentals (in the form of a Sunday evening 3 hour big band segment) and many specialized music programming blocks. WECK offers very few instrumentals and the only specialized music block WECK has is a weekly 3 hour polka music show.