Those measurements apply to string gauge - or how thick the strings are. The lower numbered set means the strings are thinner and should have less tension than the larger numbered set.
The tension on the string is a personal preference that differs among many players. Paul McCartney (probably the most famous user of Hofner basses) is said to prefer the lighter string gauge (.039-.096).
The tension on the strings is very important when you have hollowbody basses, as too much tension on the bridge can create stress on the top of the bass (even cracking the top in some circumstances). But, your Ignition bass has a center block right under the bridge. So either string gauge will work and there is really no risk in cracking the top.
I have played both sets and personally prefer the heavier (larger) of the two (.050-.100). One additional factor you should consider... The lighter string set (.039-.096) is made of stainless steel and tends to be a little brighter sounding than the "standard" or larger set (.050-.100). If your Husband likes 50's and 60's music, the larger set sounds a little less bright and better (in my experience) for classic blues/rock than the lighter stainless steel set.
That is my 2 cents. But, I don't think you could go wrong with either set.
Congrats to you for such a thoughtful gift.
Last edited by funkytoe : 11-19-2013 at 12:36 PM.