Are they not 2 sides of the same coin? Investing is saving, and saving is investing...
Spending or Saving would be a question...
Not really although both are linked they are not one and the same, because while you can invest with your savings, you can also borrow money in order to invest, and borrowing is the complete opposite of saving.
I think the saving and investment are two different things, if you're using a fiat currency as the currency can not you use your main bitcoin as a place to store money? rather it is an investment
btw you can combine the investment and saving