Obama's app was advertised as an app for the Obama campaign. People who used the app consented that the Obama campaign would get access to data about them and their friends. For better or worse (better for marketers, worse for the friends of these app users), this was all within how Facebook was expected to work.
Cambridge Analytica obtained similar data, but in a different way by breaking Facebook's TOS. A developer made an app, advertised as some kind of quiz, never saying that the data would be handed over to CA. Not only was the app developer not being up front about what the data would be used for, but they also broke FB's TOS [0] with its usage.
Plainly, there are key differences here beyond how it was heralded at the time (and it should be noted that even the article your provided shows Obama's data collection in both a positive and negative light).
0 - https://www.vox.com/2018/3/17/17134072/facebook-cambridge-an...
I see no material difference here. People shared their data and it was used accordingly. This is how Facebook is expected to work. It's not like the Obama app had a big button that said "upload your friends list to Obama's database!". That was covertly done behind the scenes.
Irregardless, all Facebook users should assume all of their data is being sold and sliced and diced a million different ways.
The main point here is that the media has tried to turn CA in to a scandal while they very much did not do that for very similar actions Obama was taking.
Obama's app was only ever installed on peoples devices that wanted it.
it was in effect preaching to the converted.
CA deliberately harvested people that were not politically involved and dissafected and whipped them into a fuhrer, and thats just how they got started and doesn't cover the outright lies they pushed and farmed.
https://www.theguardian.com/world/2012/feb/17/obama-digital-...
> "Consciously or otherwise, the individual volunteer will be injecting all the information they store publicly on their Facebook page – home location, date of birth, interests and, crucially, network of friends – directly into the central Obama database.
The only difference is that at the time it was heralded as being technologically savvy because it produced results that the media and tech companies desired.