Big difference.
All '98 5 spokes are FORGED Aluminum.
I believe most '97 5 spokes are CAST Aluminum.
The forged are much more desirable, due to strength and mirror like finish. Search the website for more info., as this has been discussed in great deal in previous posts....
Good Luck.
P.S. - Yes, '98 rims will fit on '97 no problem....