Never heard of either version, where are you buying the cpu from?
Edit: Wait, tray and box can refer to OEM and retail versions of parts, is that what you mean? If so, get the retail version unless your planning on getting an after markey hsf, the OEM version doesnt come with a hsf. Also, the OEM version of cpu's (and most other parts for that matter) come with a shorter warrenty, or none at all.
There are two options, w/only $5 separating the two. Looks like a packaging issue, but I don't know why one would choose one over the other.
Uh, for $5 bucks...get the box version.