England and Scotland are not the same country, they are members of the same union (The UK) and reside on the same island (Great Britain) but are different counties in their own right, Scotland encompassing mainland Scotland and the Scottish Isles principally Orkney isles, the Shetland Isles and the Hebrides and makes its own laws.
Wales on the other hand is a Principality of England and so shares the same criminal laws, but not necessarily the same civil ones.
Northern Ireland is a Province and is largely self governing, but can have it's laws over ridden by the Westminister.
The four countries together are known as The British Isles, a term used to mean the island of Great Britain plus the north of Ireland and many smaller surrounding self governing islands, including the Isle of Man and, in some contexts, the Channel Islands

Not the only reason there is a secession movement in Scotland.

In the United States we have as many as 50 different laws on the same subject. Usually State laws do not differ very much, but in some cases the difference is rather large.