Its not a silly question.
One is provided by Vanguard, the other by iShares - Simply put they’re two separate organisations tracking the S&P 500. The difference in share price isn’t a factor worth looking at - the key thing is to look at historical performance - how well they track the index, and fees (known as expense ratio)
In the case of these two, they’re both 0.07% and their performance have been pretty identical. iShares marginally better in the last year by decimals.
Its a question of whether you think one will track the performance of the S&P better than the other going forward. I hold iShares - this may change in the future depending on performance.