Both spelling and pronunciation are important to get a word right. Spelling is important to make the other person understand what you have written. At the same time, pronunciation is important to make the other person understand what you speak. This is another important difference between spelling and pronunciation.
In other words, spelling is important in writing, whereas pronunciation is very important while speaking English language. Wrong pronunciation will lead to wrong or at times, unclear understanding of the language. Similarly wrong spelling also leads to wrong understanding of the written language.
Spelling is more concerned about the letters used in a word. On the other hand, pronunciation is more to do with the intonation of the letters of a word. In other words, each letter has got a particular intonation by which it should be pronounced. Hence, intonation has to be right if pronunciation has to be right. On the other hand, spelling is more about the order of the letters used in the construction of a word.