Difference in what though? Satiety? Hunger? Weight loss? The underlying method for all weight loss is to eat fewer calories. How someone accomplishes that is up them and may come down to personal preference.
However, most American salads are loaded with decidedly non-healthy items, so a 200-300 drop in meal calories would be offset by the salad itself.
Better just eat them to increase vegetables, then. (No iceberg!)
Have a look for some mediterranean salad recipes, try putting some cherry tomatoes in for sweetness, a light drizzle of olive oil and swap the lettuce out for rocket and see how it goes.
Lettuce, tomato, avocado slices, chopped green onions, and an anchovy or smoked oysters with vinaigrette is fantastic, regardless of what kind of green is used as the base.
http://nutrition.about.com/od/askyournutritionist/f/lettuce_...