The standard point buy seems to be different. I'll illustrate an experience you may wish to watch out for. It's not necessarily a Pathfinder-specific thing, but could happen more easily in PF. At 8th-level, one of our players retired his rogue character and showed up with an elf necromancer. In an act of "no social skills" (very surprising for the player, who is an amazing DM, although not of D&D) he brought in a character without any sort of preview on our mailing list or wiki. It was a core-only elf necromancer. In 3.0, the standard point buy was 25 and a typical PC was expected to start with a high stat of only 15. There were no races at the start with any mental stat boosts. (I seriously doubt any group ever played a wizard with starting Int 15, they'd nerf Strength and Charisma and even Wisdom to start with a high stat. Playtesting is supposed to catch stuff like that!) Our DM has us playing the equivalent of 32 point buy (I forget what this is called in Pathfinder). The player's character started with Int 18, +2 for being an elf, and then of course +2 for levels and a +4 item, giving him an Int of 26 and having save DCs of 18 + spell level, plus had Dex and Con scores high enough to not suck. Said PC started curbstomping any and all encounters viewed. Said player is always paranoid of their PC getting hurt and so took all the best defensive spells (always either invisible or mirror image'd, the latter getting a buff it didn't need in PF)... and if they'd been more familiar with 3.x/PF rules and had taken Spell Focus once or twice, would have been even more overpowered.
I would say take 15 point buy (that's the equivalent of 25 point buy), but the high point buy made PC concepts like my druid wildshaped-focused PC vastly more viable than would normally be the case... certain types of cheese are just easier or at least less costly in PF than in 3.x.
Pathfinder goes 10/15/20/25
D&D went 15/22/25/28/32 (I think – can’t find this online), so more options.
Pathfinder 20 is comparable to D&D 28 (both levels our group played at). You could put 4 stats at 14 (cost of 5 each in Pathfinder, 6 in D&D) and 2 at 10 (cost nil in PF and 2 each in D&D). Moving out to higher stats or lower stats varies the two. There was no point buy for a 7 in D&D, while PF gives you 2 extra points (over and above the 2 for dropping to an 8). However, the incremental cost for increasing a stat kicks in earlier in PF (at even numbers, rather than the next odd number), so an 18 in PF costs 17 versus 16 in D&D, even considering the D&D character started at 8 and PF at 10 (the PF cost of selecting an 18 rather than an 8 is really 19).
So what did the Necro take? Starting INT of 18 costs 17 points. Assuming 25 point buy, that leaves 8 points. I’m guessing he nerfed STR and CHA down to, say, 8 and 7 (spell books are heavy…) so that gives him another 6 points, so 14. He can pump 5 each into CON and DEX, so 14’s (certainly doesn’t suck) and That leaves 4 to have, say, a 12 WIS and a 10 STR (or 8 CHA).
So let’s call his stats S8 D14 C14 I18 W12 Ch8 25 points (8 CHA because D&D would not allow for a 7, so tough to compare)
Same array in D&D costs 0 + 6 + 6 + 16 + 4 + 0 = 32, so equivalent point buy.
So I don’t think this is significantly less costly in Pathfinder. The only difference in Pathinder is the +2 INT for being an elf. That 1 point bonus to DC is the only difference between 3.5 and Pathfinder, so I suggest a character equally powerful could be created under either system, with Pathfinder having a small advantage due to the elf’s +2 (but a human, half elf or half orc could also assign their +2 bonus to INT). The big difference is that you can get bonuses to a mental stat, not just to a physical stat, from race in Pathfinder.
The real issue is a combination of high point build and min/max attributes, not a change between the systems.