In terms of meaning, both words function as nouns and verbs but they have a different definition. When sprang works as a verb it is the past tense of spring, and it refers to a sudden move or the release of something. When it works as a noun, it refers to a season. On the other hand, strand refers to the act of abandoning when it works as a verb, and it refers to a part of a rope when it works as a noun.
In terms of pronunciation, both words start with a fricative consonant sound; however, the word sprang ends up with a nasal sound, and the word strand ends up with a plosive sound.