Harish has not written the basic difference.
Stipend is paid under the provisions of Apprentice Act 1961. The minimum amount is decided and revised every year by the Govt. However, employers have liberty to pay more than what is stipulated. Stipend is paid to the apprentices. They are not employees, either regular or contractual. Provisions of PF and ESI are not applicable for apprentices when they receive stipend.
On the other hand, salary is paid to the employees. Employee could be regular, temporary or contractual. Rules of payment of monthly salary are governed by Payment of Wages Act, 1936, Shops or Establishment Act or Factories Act etc.
Few companies use the word "stipend" loosely without understanding their proper meaning. You may employ some person and designate him/her as "trainee", however, remuneration that he/she receives is not "stipend" but monthly salary and PF and ESI regulations are applicable.
Hope this satisfies your query now.
Dinesh V Divekar
2nd August 2012 From India, Bangalore