Complex sentence: The song was originally intended to be released on the famous "SMiLE" album, planned for 1967, but due to the cancellation of "SMiLE", it was released in a completely different form on "Smiley Smile" instead.
Split into simpler sentences: The song was originally intended to be released on the famous "SMiLE" album which was scheduled to be released in 1967. However due to the cancellation of "SMiLE" it was released in completely different form on "Smiley Smile" instead.