The ETFs are designed to replicate the return. Don't get hung up on the price.
Say you have two ETFs both designed to replicate the return of an index. Call these ETFs A and B. Whether you buy 1 share of ETF A for $100 or 2 shares of ETF B for $50, you have invested $100.
Each ETF manager will take your money along with the money of others who have bought the ETF and go out and buy the stocks in the index in the correct weights. Now, this isn't exactly the way it works but for our purposes let's assume so because if we get into the finer details of ETF creation it will just be confusing.
So let's assume you were the only investor in either ETF and the market went up 1% the next day.
- ETF manager A bought $100 worth of the index and so made $1 and the 1 share of ETF A that you bought is now worth $101.
- ETF manager B bought $100 worth of the index and so made $1 and now your two shares of ETF B are each worth $50.50, for a total of $101.
Differences such as expense ratios, inception date, inception price, and to a far lesser extent where divs are parked until distributed can all lead to price differences, holding all other behavior constant.
*Some people seem to have an inability to read the comments. If I was going to post an answer to a question, I'd read the comments first. In fact, I do.