Hi,
* 500MHz 3.3V level differential signals are not very usual. Please confirm. Maybe they are LVDS or any other IO standard.
* Then look at the receiver IC datasheets for the level requirements (common mode, differential mode, hysteresis) and max allowed input levels.
* also check about characteristic line impedance requirements and the use of termination
In simplest case you may just connect them
Next simple is that you need resistive voltage dividers. (values may depend on characteristic impedance)
Maybe you need true level converters. A search at a distributor should work. There you may also find manufacturer names for level converters. Then visit the manufacturer internet site for additional informations and selection tools.
Klaus