All 4" pots are not created equal. The conifer on the left is from Park Seeds. In the product description, they specify a 4" pot. What they meant was a 3.25" roundish pot that is 4" deep (These are my measurements, I could not find this info on their website). The conifer on the right is from Stanley & Sons Nursery in Oregon. This is their 4" pot. It is 4" square and 5" deep.
There is a considerable difference between these two 4 inch pots.
Lesson learned: beware of marketing measurements:)