What is the difference between sub surface and
sinking lines.????

Trevor
It is simply the rate at which the line sinks.Years ago there were less to choose from and choosing lines was easier.
A'Wet Cel 2' used to sink faster than a 'Wet Cel 1' for instance and an 'Aquasink' sank much faster than both.
Things are more complicated now due to the huge variety of lines available.One manufacturer's imtermediate is another's slow sinker. Faster sinking lines can also be retrieved deeper but this then depends on the rate of retrieve!! It is a nightmare!
'Sub surface' seems to relate to 'Neutral density' lines or 'intermediates' depending on maker.Ie.Very slow sinking lines which 'hang' beneath the surface and can be used like a 'Floater' without the'drag' if this is what you need' In reality a limited range of lines is all you need and find out how they work rather than buy loads of different ones. The best way is to contact someone like Steve Parton who will tell you what you need without any bullshit.
Remember the price of a line is no guide to it's usefulness to you.Besides a lot of different lines are all made by the same manufacturers!!
If you already know all this then apologies.Otherwise hope it helps

Totaly agree mate their is very little need for more than 2 or 3 lines unless you fish comps then its a little diffrent.

As the above post says ask before buying, do not ever go with this system of intermediate, slow sink etc have a look on the box and look at what speed the line sinks you will be suprised, for me an intermediate is 0.5" to 1" per second but what is the point of an intermediate when a floating line with a weighted fly and a longish leader will do the same job