Many scholors & economists don't agree with this equivalence of interest and sood. Interest is the charge for the capital you provided to others. The main thing is that it is the agreed amount, which is justified through the equilibirium market forces. If someone charges over and above that market rate of interest, then that is exploitation.
Interest is a fee or an incentive due to which you would take the risk of providing your money to someone. If there is no incentive, would you take a huge risk of giving 10 lacs to someone for a year, let's say? That person may default and you are better off not giving any loan to anyone and keep saving it in your lockers.
Riba or Sood, by definition is the money earned over a loan through exploitation. It is the excess money you charge that is not justified. The person who gave the loan charges is due to the weakness of the person who has obtained the loan. Hence the person who owe the loan money is being exploitated.
Islam has prohibited riba/sood. Interest rates are based on the economy's inflation rates, the risk of default & loss of liquidity, and is agreed by both parties i.e. the buyers and suppliers of capital. If a person charges a rate which is higher than the justified interest rate, then that is exploitation, and the excess would constitute as riba.
Obviously, only God knows the truth. The safest way is to avoid profit of any form (whether islamic or conventional banking) on money and invest the money in a commodity or property. Both islamic bank and conventional bank will give you profit over your money invested, the difference is only the process with which they will give you that return (and their nomenclature). But it's also not that simple to just consider interest as 'riba/sood'.