A Stash is a savings pocket where you can add funds anytime, earn high interest and withdraw anytime you need it, without any lock-in period.
Keep in mind that the interest rate in a Stash is a floating interest. This means if Tonik changes the Stash interest rate, all your Stashes will always follow the latest Stash interest rate.
A Time Deposit is an investment where you commit a specific investment amount to be locked-in over a period of time in return of a guaranteed interest rate. If Tonik changes the Time Deposit interest rate, the new interest rate will only apply to new Time Deposit created after the new rate is effective. Your old Time Deposit will always follow the rate at the time it was created.