One is old school and the other is new tech.
As the markets crash, lead by tech stocks, namely FB, Apple etc. the money will go somewhere.
Gold is safe, gold has been around for a long time and is a safe bet to store wealth.
But gold has a few problems, it's heavy to cart around, difficult to exchange for a coffee and generally to valuable to carry around.
BTC the modern digital gold has some of those issues.
But alternate cryptos that are pegged to BTC solve them.
And all cryptos can be carried easily (just 1's & 0's after all)
But mostly the difference, is just like crypto VS fiat, one system is owned & controlled, the other is decentralised.
https://coingape.com/bitcoin-no-more-craze-expert-says-investors-turning-gold/