You can try to minimize it all you want (in an attempt to show that they were similar offensive players???), but that 22 OPS+ difference is huge.
It's the difference between Bernie Williams and Marcus Giles. It's the difference between Stan Musial and Jack Clark. Joe Dimaggio or Hank Aaron and Danny Tartabull.
Other players that match Martinez's 147 OPS+: Mike Schmidt, Willie McCovey, Willie Stargell, Jim Thome.
Other players that match Williams' 125 OPS+: JD Drew, Rick Monday, Eric Davis, Cliff Johnson