Pointing the obvious: faster rise in power
Starting at level 0, the average array you get for characteristics in Starfinder must be roughly equal to a 20-points distribution, depending on your race/theme/pips choice (based on experience, computing the exact point buy equivalent for every combinations would be a nightmare).
From the start, you're on a characteristic level corresponding to high-fantasy Pathfinder. It's not overpowered, but strong.
Then, instead of getting one pip every 4 level (5 pips, totaling to an increase of +2,5 to a single characteristic bonus), you'll get between 4 and 8 pips every 5 levels (between 16 to 32 pips total, between +8 and +16 bonus increase spread between all your characteristics).
Of course, you won't get 8 pips every five levels, since you'll end up getting characteristics above 16 anyway. But this is a good ballpark estimation of the change magnitude.
Augmenting characteristics in both system
To balance that aspect, Starfinder restricted the magic items raising your characteristics. These items are slotless, but you can only have one for each tier of increase (+2/+4/+6) and they have to increase different characteristics.
On the other hand, Pathfinder gives access to items raising up to three characteristics at once, with no limitations regarding how many increase of the same tier you can get (so a +6 to three characteristics item, while prohibitely expensive, is something that exists). Given enough funds, you can very well get a +6 to all your characteristics.
What will be the result
If, as a player, you want to get the highest possible characteristics, you'll end up dumping two and focusing on the rest. How it will look will heavily depends on your take on your character, but it will be way more polyvalent than a standard-system PC, the gap increasing as you progress in level.
At level 20, your highest base stat will probably be a 22, topped by a +6, for a total of 28. While this is not too different from standard Pathfinder, your second stat will sit around 26, and the two nexts are either two 22 or a 24 and a 20.
If you play smart, that means you have no really bad save compared to a standard Pathfinder character. General AC should also be higher, since classes that usually dump Dex can now afford to raise it at the same time. And to finish, everyone hit like a truck, since their main stat is maxed out.
Pathfinder being balanced while thinking of standard system/power level characters, a Starfinder-system group should fare way easier. They will be on average more competent, durable and lethal. The difference will only increase with levels.
It will also open new possibilites feat-wise (people qualifying for feats they would have been locked out from before), but I doubt this will be a huge issue, since feat trees usually favor a very specific style.
