The sun shined is going to be used mostly when you want to tell someone the time of a past event. The sun shined (or shone- they are both acceptable) all day yesterday. The sun was shining would usually be connected to another past tense idea. The sun was shining while we visited the park. Hope that helps. Let me know if you have more questions. :)

"Thе sun was shіnіng." Present tense. You may say it from 6:00 to 7:00. (depends on where you are ;) "Thе sun shіned." Past tense. You may say it after the sun has exploded or something.

If that is all there is to the sentence, it is just a stylistic choice and no big difference. It isn't so much a grammatical point. Unlike a verb like "jump" ("He jumped" has a different meaning to "He was jumping"), the default idea of the sun shining is progressive, so both sentences have the same idea. The following are the same in meaning: Yesterday was wonderful. We hiked. We swam. The sun shined Yesterday was wonderful. We hiked. We swam. The sun was shining