Yup. There's a difference.
The Stagg pickup is much cheaper, but the Seymour Duncan Woody sounds better. At least to my ears.
Seymour Duncan Woody SC
Likes: Good, natural sound. Looks natural as well because of the maple wood shell.
Dislikes: Big, so might not fit smaller soundholes. Also, the cable is permanently fixed into it.
Form: Looks like a small bar of maple wood wedged in the soundhole (as seen in the pic Subversion posted) with a 1/4" cable running out from it directly.
Stagg
Likes: Very cheap, sounds decent. Can use your own 1/4" cable.
Dislikes: Looks like the singlecoil pickup on an electric guitar. A bit troublesome with all the wires.
Form: Singlecoil pickup that is wedged between the edges of the soundhole and tightened with a screwdriver. A thin wire runs from it to the 1/4" jack which is hung at the endpin of the guitar.
Personally I prefer the Woody as it sounds better, and it is simpler, easier and less troublesome to install. However, my main gripe for it is that it fits only a limited range of soundhole sizes.