In a leaked memo, Shopify CEO Tobi Lütke put limits on employees having side hustles, saying Shopify requires 'unshared attention'::Shopify CEO Tobi Lütke discourages employees from side hustles in company memo, saying their jobs require their undivided attention.
A second job is something you must attend. A "side hustle" can be picked up and put down as needed/convenient.
That's the actual difference.