Ethereum is an implementation of blockchain with defined rules, it is the same as Bitcoin is another implementation of blockchain with defined rules, it is a broad meaning, and there could be many different instances of Ethereum blockchain implementation, these instances are defined by genesis block for each of those, and all blocks that are subsequent to this particular genesis block, while
ETHER (ETH) is a native token of Ethereum public mainnet instance, and as such can be used only on this instance, but there are also other instances - for example many testnets - Rinkeby, Kovan, Ropsten - which are public as well
as other example of instances, there are private Ethereum networks, such as Nightfall instance by Ernst and Young
so basically Ethereum is much broader term than ETH (ETHER) and one should bear that in mind when talking about about crypto currencies and digesting news regarding Ethereum blockchain implementation, that does not have necessarily to have influence on ETH crypto currency