1. How are Wasabi and Samourai wallets related?
The 2 lead developers worked together and split because they had a different desire on how to implement CoinJoin (ZeroLink) in their wallet.
2. What is a ‘Sybil attack’?
A sybil attack (explained in the Bitcoin attacks > Sybil Attacks lecture, see also sybical attacks reading assignment) is when a single perpetrator creates many identities, e.g. to have better chances of achieving a certain result (e.g. in a contest where every vote counts, creating many fake profiles to get more votes). In this case, the website was allegedly accused to have many fake identities participating in the coinjoin, while in reality the users were much less. But that was an allegation: it was not possible to prove it.
3. According to the article, what is Wasabi wallet’s main advantage?
The main advantage of Wasabi is to hide UTXOs in a ‘sufficiently’ large crowd (peers) of 100 people.
4. According to the article, what is Samourai wallet’s main advantage?
SW maintains that Whirlpool makes it more expensive for malicious actors in the system to break the anonymity of other users through a Sybil attack.