Doubt in a question in TC & SE session 1

Hello!!
Just started with verbal TC & SE
for the 2nd blank in the question, after yet
my understanding: candidates show that they do get along well in public but behind, the candidates have differences and the campaign doesn’t show there differences.
As they are trying to hide the difference, the contrast of it would be they are similar, this is how I approached the sentence without the blank & in 2nd blank I had answer similar.
Please help me to understand why similar can’t be the answer

Their campaign hide the differences , so are those campaigns actually similar or they just show they are similar??? They show they are similar and that is not the main idea in part 2, Its concession

Part 1: Their campaign are …
Part2: The politicians are different , even though they show their campaign similar, hiding their difference (The main idea is not the part even though, that is saying they pretend they are same but in reality they are different )
so if someone is different but showing their campaign simliar, how would you feel about them, are they faking it or are they doing it for real

The word “yet” does introduce a contrast. The phrase “important differences” suggests that the candidates are different from each other. However, these differences are often obscured or hidden in their campaign advertisements, which is why the advertisements are described as “smoke screens of smiles and empty slogans.”