Silkscreened decals are the type of decals that come with most commercial kits - Airfix, Revell or Minicraft type. They are printed by a professionnal printer.
Each subject is printed on a varnish layer, which slides off the carrier paper when it is soaked in water. They are the traditional waterslide decals we all know and like : the decals of our early modeling memories.
As the name implies, laser decals are printed with laser printers using toner and not ink as in silk screening. For this reason the colours white, silver or gold cannot be printed. They are the original F-decals but the pioneer era is over and these decals are now widely spread in many fields and forms.
The whole decal set is printed on a blank decal page. The varnish covers all the sheet. Compared to silk screened decals you not only trim off the carrier paper but the varnish layer as well.
Laser decals are very transluscent and must be applied over white surfaces. When you trim them off the sheet, colours look very light but, as you will find, this effect vanishes once the decal is applied.
Just trim off the subject, dip it into water and slide it on to the kit. These decals are easy to use and require no particular precaution.
The can be coated with a clear coat before or after applying them but this is by no means compulsory.
They support decal softening solutions.
Directions are basically identical. Because they are not made industrialy they can be or feel more fragile depending on decal paper consistency.
Clear coating is not necessary before application but if you wish to do so you should use an airbrush and apply light coats. Clear coating after application is fine and obviously up to your taste.
Decal softening solutions are supported too.