What the difference between 'whether' and 'If'?

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Answer

http://www.quickanddirtytips.com/education/grammar/if-versus-whether

Answer

Whether - expressing a doubt or choice between alternatives

"I'm going whether you like it or not"

If- expressing a conditional statement. An event will occur when the condition after the word 
"IF"is met.

"If the rain holds out, we can walk"
 "If it takes me seven years, I shall do it"

Answer

Whether - expressing a doubt or choice between alternatives

"I'm going whether you like it or not"

If-  expressing a conditional statement. An event will occur when the condition after the word "IF"is met.

"If the rain holds out, we can walk"
"If it takes me seven years, I shall do it"