What are the differences between seed cones and pollen cones?

The proper name for seed cone is megastrobilus (plural form is megastrobili), but it is also known as a female cone. The proper name for pollen cone is microstrobilus, but it is also known as a male cone.
Pollen cones tend to be located on the lower branches. They survive just long enough to release pollen. Since they wither, there is little evidence of their existence after pollination. They also tend to display less structural variation than seed cones among different species.
When people imagine conifer cones, they are most likely thinking of seed cones. Seed cones are both larger and longer lived than pollen cones. After pollination, megastrobilus scales will both harden and darken. They are the ones you find on the ground around conifers. Due to their structural variation, they are often used to identify different species.
http://www.pinetum.org/Lovett/pinecones.htm

https://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cones.htm