What is the diffrence between Pressure …

A pressure group can be described as an organized group that does not put up candidates for election, but seeks to influence government policy or legislation. They can also be described as ‘interest groups’, ‘lobby groups’ or ‘protest groups’.
Pressure groups (or interest groups) and social movements are hard to distinguish from one another.  They have a lot of similarities. 
The difference, though, is that an interest group is generally more of a "mainstream"  group that tries to influence the government in conventional ways. 
By contrast, a social movement is usually more of an "outsider" group that has to resort to unconventional ways of getting its point across.
Interest groups can include groups like the Chamber of Commerce or an interest group in favor of closer ties with Israel.  These groups have power and act by giving campaign donations to politicians, helping them write legislation, and other such "inside" tactics.
By contrast, social movements start out as outsider movements like the Civil Rights Movement.  These movements lack the ability to do "insider" things and therefore resort to things like protests.