Two offers can look very similar until you break down the numbers.
One store might have a larger discount but charge for shipping. Another may offer a smaller discount with free delivery. Depending on the original price, the second deal could easily be cheaper.
A deal comparison calculator can help you look at both offers side by side and see which one gives you the better value.
When comparing deals, do not stop at the discount percentage. Check the final price, coupon value, shipping cost, taxes, and any extra fees.
The best deal is the one that makes the most sense after everything is included.