I am having several issues making sense of the new OS X 10.10.3 Photos app after using iPhoto for years. I imported some photos and am used to them splitting events by date into separate "Events." I don't know what the equivalent is for "Events" in this new product. Am I required to make a new album for each date if I want them separated? Is there a "manual" of sorts for the new app?
If you haven't already, turn on the sidebar (View menu > Show Sidebar). At the top of the sidebar is a button labeled Photos. That will show you all of your photos divided by date (multiple "events", or photo groupings, for each date will appear if there is more than one location involved). Beyond that, no, there is no feature directly comparable to Events in iPhoto, though you can create albums if you want to combine multiple "events".