The difference is BTC was first and has the network effect. Litecoin solves no problems or has any practical daily use over Bitcoin, the issue of BTC transaction times is moot, there are many 3rd party solutions to deal with the slow transaction times now. The dream of LTC being a cpu-minded, truly decentralized coin is dead too. So why keep it around?

In a better world it would have been peercoin that pumped to a multi-billion dollar market cap last year, at least it brought something new to the table.