I've done both (tried SW stuck with WW since February) so I hope I can help a bit although I'm not an expert on SW (or WW really).
They are both calorie restricted diets that work in different ways. WW "Filling and Healthy" is pretty similar to SW "Extra Easy" in that they give you a list of foods you can eat and claim you can "eat until full" and still loose weight. WW (or my leader) still emphasised portion control whereas the SW consultant I met (a very helpful lady) was adamant that there was no "portion control" you eat until you felt full and if that happened after half a plate of dinner or 2 helps so be it, when I said the word "calories" she reacted as if I'd sworn at her, almost and was very evangelical about the SW approach. She was also honest that it was very finely balanced and you had to follow it to the letter. Which is pretty much the same with any diet plan. I think the "Filling and Healthy" list is slightly more restricted than SW "Extra Easy" but I haven't looked at those books in a while. The way SW do what it basically portion control is to insist that you must eat 1/3 Superfree (ie most fruit and veg) per plateful, so that even if you have 2 helpings of food its the "right" food to satiate you and you aren't
Both of these plans give you points or Syns where you can count food that isn't on the list e.g. anything from a chocolate bar/alcohol or flour/oil/pureed fruit. The standard is 49 Pro Points per week for WW and 15 Syns a day for SW, which I think work out at roughly the same number of calories. SW you also have "Healthy Extras" to choose every day depending on which plan you follow which is basically limited amounts of dairy and fibre/fat. WW allows for those two but they aren't counted as extras, just in the list of things you can have.
WW is famous for its Points system which you calculate and weigh portions of any food based on the Nutritional Values. This encourages portion control of carbs, protein and fat. Most fruit and veg have zero points so you can in theory eat as much as you want, although in practice eating 10 bananas a day isn't going to help your weight loss. On the old points fruit was counted, but since very few of us got over weight from gorging on pineapple WW wants to encourage us to pick up the apple rather than the cookie that used to be the same points.
People are given a certain amount of daily points, the 49 weeklies for flexibility and you can also earn activity points with exercise.
SW also have a low carb more protein plan and a "more carbs more veg less meat" version and I think you can switch around during the week.
Personally I'm on points and I try to have a majority F&H food each day and count it even so. Portion control has been one of the most beneficial things of WW for me. Another is the flexibility if I want a M&S sandwich I can, as long as I point it accurately and track it as part of by dailies or weeklies. It means I can go out at the weekend If I save my 49 weeklies for blowing at once and still loose weight.
SW is a plan that works for a lot of people but it relies on cooking from scratch to a big extent and I could see I was going to spend all weekend and the evenings cooking, which I really can't do for practical reasons. WW does encourage that too, especially with F&H but it has more flexibility IMO, which works best for me now. Hope that helps a bit.
