Testing: Testing is a constructive process through dis-
structive process.
Testing is done / executed to check the quality of the 
code, stability of the code, resistability of the code - 
the user input ualues.

Development: Development is a process of providing a 
solution.
Development is a process of approaching a solution a 
problem.
Eg: Custom Need his application to generate random numbers 
by accepting some valid values (Characters, Numericals, and 
Alpha Numeric char's only)from the user.
→ Developer will desing a input place / field
→ Accepts all the valid values defined in the requirement
→ He checks is it accepting the char's →→ called as Unit 
Test
→ Then Developer rights some code to for generating random 
numbers which is not hard coded with the code.

:-) then he says now your build is ready.

Testing is done here to check the implementation is correct 
at all the modules. If you feel that you need more info 
Mail with this question as subject line.
thanks and regards
praveen.v.n

Testing is nothing but checking the application whether the
application is working according to customer requirements 
or not n Development is nothing but developing the 
application it means modifying the application according to 
customer requirements.

In Development,developer's are building/developing the 
application/project as per the client given requirements.

In Testing,tester's are checking/validating the application 
whether it is working as per the client given requirements.