Saving - is putting money aside, bit by bit. You usually save up to pay for something specific, like a holiday, a deposit on a home, or to cover any emergencies that might crop up, like a broken boiler. Saving usually means putting your money into cash products, such as a savings account in a bank or building society.
Investing - is taking some of your money and trying to make it grow by buying things you think will increase in value. For example, you might invest in stocks, property, or shares in a fund.
Exactly if you have a lot of money that you won't spend for a long time you invest it, you only need a relatively small amount of savings for specific things. Savings don't earn you much (a little bit of interest is all).
Don't save a lot because it is useless and only save for at least up to 6 months of your expenses and treat them as an emergency fund and other than that. Just do investing because it will help you to grow your money faster and it is better than savings because if you are just saving then the interest rate is very low and you might be losing some investment opportunities.