The book on the left is from my files, and is a first printing of Infantry Journal / Penguin Book S229. The second scan is from Kenneth R. Johnson, an avid paperback & digest collector from Massachusetts.
This is an undated second printing and, unlike the first printing, is NOT co-published with Penguin Books, but was issued by Infantry Journal alone. The back cover ad list includes J102, which indicates that it was probably issued in 1945. Apparently, when Ian Ballantine left Penguin Books, he took the publishing deal with Infantry Journal with him. It was known that the two J- numbered books were issued during this period; one of them was later reissued with a Bantam-style dust jacket. My copy of S229 is the first documentation I have seen of a former Penguin Book being reissued by Ballantine during this period.