The top image shows the stand alone price for the Premium Deluxe version of the sim, also noting it has a 20% discount ($95.99 for game pass holders) against its normal retail price of $119.
The bottom image shows the cost to upgrade to Premium Deluxe, to obtain the same additional content. Granted, at $84.99 it is more than the difference between the standard version and Premium Deluxe, but it is quite a common practise for bundled products to be offered at a more favourable price point to entice people to spend more.
If the additional content has enough appeal to you then, yes the upgrade option is the most cost effective route.