Earlier on in the thread the vast choice of fly lines available was mentioned and how 'complicated' it is to make an appropriate choice. For simplicity, although there are many variations, the choice basically falls into 3 camps and I've chosen three lines to illustrate the point - Mastery Titan, Rio Elite Technical Trout and Mastery Competition . . .
The profile of - 1. the Mastery Titan, short head, very short front and rear tapers, effectively makes it a shooting head despite it being one continuous fly line. It loads the rod quickly, good for delivering large flies at distance. Because of the 'easy loading', shorter heads that need to be carried outside the rod tip, they're often popular with less experienced casters. Downside? Presentation can be 'heavy', roll casting is limited as are 'presentation casts mends, slack line casts etc.
The profile of - 2. The Rio Elite Technical Trout. A much longer head, with longer compound tapers. It has a long front taper to allow controlled turn over of longer, light leaders for the presentation of smaller dries and nymphs. The longer, more gently tapered belly and rear taper provides stability in the air over distance and the length of tapers provide the vehicle for controlled roll casts and presentation casts.
The profile of - 3. The Mastery Competition, defines it as a line for long casting. This does not mean that if you buy one you will cast further. If you're used to a profile like the Mastery Titan, you'll probably cast less far with the Competition. The Competition is a line for people who can consistently generate and maintain the line speed to hold 70+ feet of line in the air. It is a competition line . . . not much of a fishing line.
All the weight forward. single handed fly lines on the Sportfish website are variations of these three types.