These are two different node type properties for two different features.
cq:lastRolledout is a property of Multi site management feature where in it defines the relationship between blueprint and live copy. When the blueprint page is published, a rollout is started and then the cq:lastRolledOut date will be modified on the live copy. Documentation reference at [1]
cq:lastReplicatedBy is for replication feature where in a node is transferred from author to publishers/others. Documentation reference at [2]
[1] - https://experienceleague.adobe.com/docs/experience-manager-64/developing/platform/custom-nodetypes.h...
[2] - https://experienceleague.adobe.com/docs/experience-manager-64/developing/platform/custom-nodetypes.h...
