It's hard tell from the pictures, but the lack of details may be due to the strike, and not wear. Most coins from Denver and San Francisco in the early 20's had poor strikes. David Hall writes, "this is the first issue in the Walking Liberty half dollar series in which strike can be a definite problem. From here on out...until the last S-Mint was struck in 1946, most of the S-Mint Walkers have weak stirke problems, some severely so. It is not unusual to find mint state 1923-S half dollars that are very weakly struck on Ms. Liberty's hand and the central devices on the reverse." (Via the PCGS Coinfacts page for the 1923-S 50C). There isn't a lot of wear in the fields of the graded coin. If you look away from the high points, it does appear similar to a typical Choice VF/XF coin.
It's a very weak strike, which happens for 23-S. I looked at pictures of a 23-S in VF30 and XF45 on CoinFacts to see where the difference was. Take a look at the drapery over Liberty's right shoulder. It looks XF. The detail on the branch on the reverse also looks XF. The surfaces looks like they might have a little luster, too, so again XF. Will it get strong XF money? No. A cursory look at auction prices shows a huge variation for XF40, and this is probably due to the variation in strike.
They both look about 40 to me; full outline of breastplate but loss of detail down the body and left leg; still some rounding of the body and leg on top coin even thought the left hand is worn away.