All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is a consensus of opinion among Muslim scholars, former and later ones, that Riba (interest and/or usury) is strictly forbidden, with the exception of a later person who is not a scholar even though he is called one. In other words, all scholars of Islam prohibit Riba. Anyway, the irregular opinion of such a person constitutes a violation of the Quran, Sunnah and consensus of Muslim scholars. Thus, one is not allowed to adopt such an opinion.
On the other hand, a person who has some knowledge in Sharee'ah and transactions of Islamic and non-Islamic banks should not confuse profits of Islamic Banks with the interest of non-Islamic banks.
In fact, a transaction between an Islamic bank and its customers constitutes a form of Mudhaarabah (profit-sharing). In simple words, the customer gives the money to the Bank which is the 2nd party that invests the money, then if some profit is received, the customer will take some percentage of it, and there is no harm if it is different from one year to the other.
But the usury-taking-banks receive the customer's deposits and fix the percentage of interest instantly without any possible loss in the future. This, in fact, is pure Riba.
Also, we cannot compare the two kinds of banks although there are some possible violations of the Sharee'ah in the practices of Islamic banks. Then, such latter banks were established as substitutes for the usury-taking-banks, which are based on Riba.
Allah Says (what means): {…But Allah has permitted trade and has forbidden interest...} [Quran 2:275]
Here, we state that most wrong practices of Islamic banks result from following weak opinions of some scholars. For sure, it is a duty to follow proved and authentic opinions as well as to avoid weak ones whatever their sources.
Also, we re-state that we should follow proved opinions, and if some committees of censorship in Islamic Banks do not follow such way on the plea of making it easy for Muslims, they are wrong unless they abide on the Sharee'ah rulings and principals that do not contradict the proved opinions.
Allah Knows best.