I was picking this title for this post because I saw too many Ethereum vs EOS articles. If blockchains will be mass adopted, there will not be a single blockchain platform. If not(It's hard to believe that now, but you never know), none of them will become so relevant. So, beside technicalities how similar are they?
Ethereum has a vibrant community, an experienced team and many tokens defined in it so it will be really hard to replace ethereum. Soon they will migrate to PoS and the fees for transactions and running contracts will probably get much lower.
EOS comes with all the advantages Steem has. Fee-less transactions, huge number of transactions per second and it relies a lot on steemit and bitshares communities. They are probably using the existing Steem and Bitshares codebase and probably many of their devs joined the EOS.
In the coming year(s) Ethereum will probably dominate the space. Currently, with a few exceptions, blockchain technologies are pure speculations, but soon the blockchain technologies will evolve and will become part of day to day life. Slowly waters will split for ethereum and eos.
Ethereum target is closer to financial sector, while eos is a platform for all kind of apps, like steemit.
As both of them will grow, they will be more similar. Ethereum migrating to PoS and having new dapps to make smart contracts friendly to all kind of people and EOS trying to make as easy as possible to develop apps. To some extent they will be like linux and windows: ethereum having it's own cryptic language, while EOS will be able to run any code compiled to webassemblies.
We can see how difficult it is now for ethereum to take the leading place owned by bitcoin. I will be even more difficult for EOS to challenge an Ethereum which has an active development team. On the other side, there will not be only one blockchain platform and both Ethereum and EOS can co-exist.