You can compare data from two different periods of time using the timeline at the top of Tiles.
Step 1: Select a period of time by clicking and dragging on the timeline.
Step 2: Click the compare link at the top right of Tiles.
Step 3: Adjust the date range or comparison range by either dragging the highlighted range or by manually entering the desired date/time range in the text input field at the top.
Shortcut keys:Arrow Up / Arrow Down: Click on the input data/time field then click the arrow up / arrow down key to increment / decrement its value.
COMMAND (Mac) / CTRL (Win): When dragging the highlighted range on the timeline, the selection will snap to minor gridlines when pressed otherwise the selection will snap to major gridlines on the timeline.
ALT: With a timeline range selected, click on the range holding ALT to initiate the compare mode highlight.
Demo Video (1:17):