Ordnance Survey® (OS) the mapping agency of Great Britain and provides detailed high quality maps. Memory-Map were the first company to licence OS map data to produce digital maps for outdoor recreation. Memory-Map's OS Landranger 1:50,000 and OS Explorer 1:25,000 maps look identical to the printed versions provided by Ordnance Survey® themselves.
The main difference between the two map is scale. Scale is the number of times that you would need to magnify the map for it to be the same size as the real world or the number of times that the real world has been reduced in size to become the map.
OS Explorer (1:25k) Mapping
The OS Explorer Map is at 1:25000 scale (so 4cm on the map equals 1km in the real world). It shows great detail of the area the map is covering including footpaths, rights of way, open access land and the vegetation on the land. This is the map that you’d use for your outdoor activities such as walking, horse riding and off-road cycling. An example of what this map looks like is shown below (click on the picture to enlarge it):
OS Landranger (1:50k) Mapping
The OS Landranger Map is at 1:50000 scale (so 2cm on the map equals 1km in the real world). The map will cover a larger area that the OS Explorer Map but not in as much detail. You’ll still find footpaths, rights of way and some tourist information features on the map. Whilst you do lose some of the detail such as open access land on this map – it is still possible to use it when out walking for navigation with your compass. This is the map they you’d use for days out or short breaks and even road cycling as a larger area is covered. An example of what this map looks like is shown below (click on the picture to enlarge it):