Tamiya follows it 1/48th F-35A Lightning kit with a new and very updated 1/48th F-35B. I have been lucky enough to review both. The F-35A Review is here: https://reviews.ipmsusa.org/review/f-35a-lightning-ii-4
For this review, I will focus on the differences between the two kits. Inside the box, you will find 14 sprues with tress A, B, C and E being carryovers from the A version. There are sprues to make weapons also: