Yeah but again we're coming up against safe archaelogical assumptions based on findings. But when we're talking Saxons and Frisians I find it hard to fail to mention the Angles and the Jutes.
INTPenis is mentioning Angles and Jutes because they were in present day Denmark (and England). You might ask what the cultural difference is, from Vikings, and I'd flounder. Vikings spoke Old Norse, a germanic language related to whatever the other tribes spoke (um, West Germanic, such as Old Frankish). They believed in gods related to the gods of these other tribes and used similar runes.
If you want to say this is an arbitrary modern set of categories ... I guess the Romans are responsible for the categorization really, by writing down tribe names such as Frisii.
Well, it's fair enough to observe that the Vikings spoke a North Germanic language while the Angles, Saxons, Jutes, Franks, and Frisians spoke a West Germanic one. Other than that, it seems pretty clear that the category "Germanic groups such as the Saxons, Franks, and Frisians" would include Vikings. "Such as" isn't exactly the mark of an exhaustive list.
(And interestingly enough, the cognate word ("wicing") is attested in Old English a long time before it's attested in Old Norse. It means "pirate". It wouldn't be at all surprising if Saxons raiding England referred to themselves that way, just like Danes raiding England did later.)
Confusingly, though, there's the chance we might still not be talking about real cognates. The Old Norse víkingr can be derived from (Old Norse) vík (inlet, cove, fjord) + -ingr ('one belonging to', 'one who frequents'), or possibly even something close to Old Norse vika (sea mile), originally referring to the distance between two shifts of rowers, ultimately from the Proto-Germanic ~wîkan 'to recede' and found in the early Nordic verb ~wikan 'to turn', similar to Old Icelandic víkja 'to move, to turn', with well-attested nautical usages.
The Old English wīc, on the other hand, has an old Germanic etymology referring to 'camps', 'villages' and the like.
God knows there are a lot of inlets and fjords in Scandinavia, which incidentally were also places from where the surplus "víkingr" males surged west, possibly having adapted the term as an ethnonym by then; at least in modern Scandinavian languages cognates like 'viking' (pl. 'vikingar') are definitely associated with the geographic root 'vik' — as are innumerable surnames like Sandvik, Vikman, etc. Then again, those roving Vikings did of course build up "camps" and "settlements" wherever they went, although this perhaps sounds more likely a name someone else would give to them...
As for the difference between the Norse (ie North Germanic/Scandinavian) tribes/people and their more southern cousins (Angles, Saxons, Franks etc.) prior to and at the beginning of the Viking era, you might say the former were in fact quite clearly relatively more isolated in terms of geography, language and still-very-much-pagan culture. (And while eg Angles and Saxons did invade and settle much of Britain from current Northern German and parts of Denmark, this was already a couple of hundred years before, and a lot happened since.)
This site suggests "Germanic groups such as the Saxons, Franks, and Frisians". That seems like the more parsimonious explanation.