There isn't a whole lotta depth to SJ. After playing many games digitally and IRL, SJ got bland for me, whereas, I still continue playing RftG. These days, the SJ exp needs to be included for me to play SJ, and this is still vs. base game RftG. On the plus side, SJ with the exp is still easier to teach than base game RftG, so I don't feel bad pushing SJ + exp on non-gamers or those otherwise not able to handle Race. That's the one con of RftG... if you're teaching it to a newbie and he's only going to play it once, it may not be as worth it. Back to back games are nice, but even once every week or even month can cut it, but if it's a game he won't play again for another year or 8 months, then... :(
Speaking of which, you can install a Window's version of RftG here (Keldon's AI. Works on OSX and Linux, bjut with some alternate compiling)
and the highly recommended UI patch here (just copy the files to the same install directory)...
SJ base game can be found on iOS (AppStore) and the Java version for PC below...
Search for Condado on Google Play for SJ with exp for Android
Race indeed has more depth in where with RftG...
-almost every decision point and turn is done simultaneously
-you can also get VP by earning VP chips (unlike SJ where everything's strictly pts from buildings)
-another end condition is also running the VP chip pool dry
-it's not just one type of building phase... the "buildings" in Race are divided into Developments and worlds, and each have their own phases for when they can be built.
-the worlds are divided into military worlds and non-military worlds. As you've seen, non-mili-worlds cost $$, but can always be built if you can wrangle enough wealth. OTOH, you can have all the wealth your hand limit will allow... but if you're one military strength short of a conquering a mili-world's defense, it's useless to you. If you can afford it though... it's free :)
-you have temporary cards that get discarded from Tableau... granted that the Crane in SJ does have a unique mechanic that lets you build over buildings, which RftG won't come to a close equivalent until exp #3's Terraforming Engineers
-the lesser types of goods can be VERY valuable... the blue goods can be sold for more cards due to trade specific powers for blue. Otherwise, lots of blue goods means you overall got those worlds for cheap and have more "power" in producing and consuming (converting goods to VP). In SJ, it's linear... Silver is almost always superior to Indigo
-the 6-cost devs in RftG (that give variable pts) also have powers, whereas the 6-costs in SJ are strictly for points... no engine boost whatsoever.
many people compare RftG and SJ and consider them to be more similar to each other than RftG vs. Puerto Rico (PR). The comparisons are far from black and white...
RftG & SJ: are similar due to them both being card games of that nature (using cards in hand to pay for other cards).
SJ & PR: both have the same theme... Governer, Library, indigo, coffee, markets, and that part of the world during that time period
RftG & PR: both have a mechanic to convert goods to VP, multiple end conditions, reasons to get inferior goods vs. the better ones, etc.