We compared the newer Timeline Blister with the older (discontinued) square tin Timeline to find out are what the the key differences. Can the new timeline be used with the old timeline? 

These are the key differences:

1. The tin is significantly smaller.

2. It contains half the cards of the original (55 vs 110).

3. The newer packs cost less.

4. The older cards have more rounded corners.

New vs Old Timeline Cards - Rounded Corners
5. The text box and year appear slightly different.

6. The cards are the same size as the original.

So they are compatible, you can mix and match old and new.