In Two party-system two major parties compete for power while in multi-party system more than two major parties compete for power.
A... Strengths of two party system are :
Easy government formation.
Strong Opposition.
Government completes its full term.
Easy elections.
B.... weaknesses of two-party system :
Masses are less represented.
Less choice for voters.
1. Strengths of multi-party system :
Masses and minorities are well represented.
More choices for voters.
2. Weaknesses of Multi-party system :
No easy government formation and coalition government.
Coalition often breaks before full term of government.
Money and time consuming elections.