Geometrical Isomerization
cis and trans are older notations that express roughly same concept of E and Z.

Explicitly, E and Z have absolute meaning and are assigned based on precedent, where the Z is assigned to the case where the highest priority substituents are on the same side of the alkene/double bond and E being opposite.  These notations explicitly refer to a pair wise relationship.  It is not normally said '... the group E to the ...'

cis and trans refer to substituents of context, with cis being substituents on the same side of the alkene/double bond, and trans being opposite.  Frequently these refer to the most important nomenclaturally, but not always.  Additionally cis and trans are used in discussions such as '...the group trans to the ...' describing a relation of one object relative to the other.  cis and trans are no longer considered IUPAC-correct nomenclature, but still have some usage for descriptive discussion.