difference between complete and finish

• There is no difference, "complete" is one of the definitions of finish. The only difference is "complete" sounds slightly more formal and sophisticated, and you would usually use it to say things like "I completed the task"; you would usually say "I finished the race" instead of completed, although you can switch them if you want pretty much in every case.

• i ll explain in this way..
  "When you marry the right woman, you are COMPLETE. But, when you marry the wrong woman, you are FINISHED. And when the right one catches you with the wrong one, you are COMPLETELY FINISHED!"
  
  
• Complete and Finish are two words that are often confused due to the appearing similarity between their meanings. There is of course some difference between their connotations. Hence it is not correct to interchange them. The word ‘complete’ is used in the sense of ‘entire’ or ‘total’. On the other hand, the word ‘finish’ is usually used in the sense of ‘conclude’ or ‘end’. This is the main difference between the two words.
  The word ‘complete’ is used as a verb, and in the sense of ‘to do entirely’. On the other hand, the word ‘finish’ is also used as a verb, and it is used in the sense of ‘come to an end’. It is interesting to note that the word ‘complete’ when used as an adjective gives the sense of ‘entire’ or ‘total’ as in the sentences,
  1. The complete work was done by the team.
  2. Francis read the complete book.
  In both the sentences the word ‘complete’ is used as an adjective and hence, the meaning of the first sentence would be ‘the entire work was done by the team’, and the meaning of the second sentence would be ‘Francis read the entire book’. Observe the two sentences wherein the word ‘complete’ is used as a verb.
  1. The work was completed by Angela quickly.
  2. Robert could not complete the work in time.
  In both the sentences, the word ‘complete’ is used as a verb and hence, the meaning of the first sentence would be ‘the work was done entirely by Angela quickly’, and the meaning of the second sentence would be ‘Robert could not do the work entirely, in time’.
  Take a look at the following sentences to understand the usage of the word ‘finish’.
  1. The story finished well indeed.
  2. How are you going to finish the play?
  In both the sentences, the word ‘finish’ is used as a verb and hence, the meaning of the first sentence would be ‘the story ended well indeed’, and the meaning of the second sentence would be ‘how are you going to conclude the play?” It is interesting to note that the word ‘finish’ at times can be used as a noun too as in the examples,
  1. The runner hit the finish in record time.
  2. The movie had a great finish.
  In both the sentences, the word ‘finish’ is used as a noun.