Brains consist of cells called neurons and they connect with millions of other neurons and information gets transferred across connection gaps called synapses. Inside the cells data are processed which gives rise to an idea, concept or understanding.
Computers are built of hardware chips and the central processing unit (CPU) processes data after receiving them from the other chips. How it processes data consists of several steps but the main outline is that software programs are fed into the CPU and processed. They provide end result information depending on how the programs are furnished with data and what the query is that is fed into the system. If some information is asked that is outside the scope of the software programs, the computer gets limited in functioning.
Brains, however, are limitless. From childhood until adulthood, the brain gets more and more developed and mature. It can process unknown data or abstract data as well and provide insights and knowledge.
The brain is more complex than the CPU and therefore, with neurons and synaptic connections, it is possible to process all kinds of information. It uses the five senses: touch, smell, hearing, taste and sight and takes in information and produces knowledge.
On the other hand, the CPU of computers takes in data from the typing of the keyboard and processes it, which is very limited. However, it is only human beings feeding data, writing software programs and making the computer behave like a brain although not quite so.
The brain is still more intelligent than the CPU of computers and has yet to train the computer to behave like the brain of a human being.
Yes, computers will be able to take over many tasks of human beings but without human beings, they are lifeless because humans have to give life to these computers, operate on them and have regular updating, monitoring and maintenance on them.
Just as a brain needs to rest and relax, computers will also need that from time to time but they can operate longer times than the average brain. While the brain sleeps, the computer can carry on with its duties of processing data and converting them to knowledge and information.