I know that both of them are probably wrong and have errors, but these are the lists for the top 10 best-selling PS1 games, and then PS2 for each website.
PS1
Wikipedia
10.Metal Gear Solid
9.Crash Bandicoot 3: Warped
8.Tomb Raider II
7.Harry Potter and the Philospher's Stone (seriously?)
6.Final Fantasy VIII
5.Tekken 3
4.Resident Evil
3.Gran Turismo 2
2.Final Fantasy VII
1.Gran Turismo
VGChartz
10.Metal Gear Solid
9.Driver
8.Crash Bandicoot
7.Crash Bandicoot 3: Warped
6.Tekken 3
5.Crash Bandicoot 2: Cortex Strikes Back
4.Final Fantasy VIII
3.Gran Turismo 2
2.Final Fantasy VII
1.Gran Turismo
PS2
Wikipedia
10.Kingdom Hearts
9.Final Fantasy XII
8.Tekken 3
7.Final Fantasy X
6.Metal Gear Solid 2: Sons of Liberty
5.Grand Theft Auto III
4.Grand Theft Auto: Vice City
3.Gran Turismo 4
2.Gran Turismo 3: A-Spec
1.Grand Theft Auto: San Andreas
VGChartz
10.Kingdom Hearts
9.Medal of Honor: Frontline
8.Need for Speed Underground 2
7.Need for Speed Underground
6.Final Fantasy X
5.Gran Turismo 4
4.Grand Theft Auto III
3.Gran Turismo 3: A-Spec
2.Grand Theft Auto: Vice City
1.Grand Theft Auto: San Andreas
Looking at these, which one do you think is closer the actual lists