I picked up these two cards at last month's Tokyo Card Festa. Both are from the same set, but there are a few differences.
Both are printed on white bromide stock, similar to photo paper, but a little thicker. They have a glossy finish, and are the same size - basically standard trading card width but just a tad bit taller.
These were both issued in 1988 as part of JBR 22: Pure Card Type Color (or "Pro Baseball popular player bromides"). They came in blue paper pouches just like other bromides, and were probably produced by Amada (Engel says maybe IFT or Amada, but I'm taking sides.) Like most bromides, these were probably unauthorized, but they're professionally done. Amada has gone on to do major trading card sets for all sorts of subjects. I sometimes see auctions for full packs of these bromides on YJA.