No it does not matter to 99.9% of the gamers that will be buying these launch games.

Yes, it may be slightly noticeable if playing side by side. Otherwise, no, not really noticeable.

listen up all developers... 720p games is good enough for next gen console and don't waste effort making 1080p games cause its not important to most gamers...

COD will look great on both systems... but it will look better in 1080p. 

Take 50" screen

Compare side by side

Notice.

All that resolution talk doesn't make sense. The power gap is nowhere near big enough for a 720p vs 1080p scenario at similar settings, if it is, then we might as well disregard every spec released so far for the Xbox One and put it along with the Wii U in regard to graphics. The bare minimum expected would be a 900p vs 1080p or something like that at the same settings, all that 720p talk is unrealistic except if somehow the One version has double the polygon count or something like that.

These are launch games, they will better

That's kind of what I have been thinking.  My other thought is that if the XB1 is going to be at 720p this year, they will both be at 720 next year when the games demand even more from them.  THe power difference is not that much and 3 years from now, both systems will be struggling if the developers try to max out the games.

This is a question best left unanswered until mid-gen.

Did it matter for PS3/360? To some extent, absolutely. There are often differences in multiplats (albeit marginal) but they do exist and there is a reason to address them.

If I were a betting man, I would presume there will be slightly more noticeable differences for this generation.