Both are 2-litre engines used in VW's Golf and Scirocco models, (as well as by the Audi A3, A4, A5, TT and other VW Group products). The EA888 is the latest of the two engines; it's used in the Golf GTI and develops 210 bhp. The EA113 is used in the Golf R and develops 270 bhp. The EA113 was previously used in the Mk 5 GTI and developed 200 bhp. The EA888 is more fuel efficient, with lower emissions and is apparently easier to build than the EA113. Given that the EA113 had already been tuned for service in the S3, it was easier and cheaper to simply stick this older lump in the R than develop the new EA888.
I suspect that fuel consumption in the Golf R may be significantly higher than that in the GTI. I am looking forward to reading the first road tests before I commit. If the R's price is steep too, the GTI's newer (and presumably better) engine may just tip the scales in its favour, especially now that the R's rear LEDs are available for its lesser sibling.
On the other hand, new doesn't always equal better. The EA888 may not be better at all; it may simply be a dumbed-down version of the EA113.
Anyone know anything more about this?