For many of those wish to know the difference between Blockchain and a database, it is best to start by simply explaining that they are different in design, the way these technologies operate.
A database that runs on the web is mostly using client-server network architecture, which means that a user with permissions associated with his account can change data and entries stored on a centralized server. If the master copy is changed, users will get the updated version of the database entry every time they access the web from their computers.
Blockchain has a totally different system regarding these data and entries. For a Blockchain database , users are those who maintain and update new entries into the database. All nodes work together to determine that they are all making same conclusions, which results in having an inbuilt security on the network. Both systems have their advantages. Blockchain is good for keeping a record of certain functions, while centralized database in good for other types of roles.
Decentralized system of control
If two users don't trust each other and don't wish to share the information without requiring a central administrator, it is completely allowed when using a Blockchain. In this technology, transactions are processed by a huge network of users who act as intermediaries, making sure that everyone is creating the same shared system of record at the same time.
The good thing about decentralized control is that it eliminates any risk of existence of centralized control. By using a centralized database, anyone with enough access to the system can delete or corrupt the data stored in it. This is where users become quite dependant on the administrators.
There are also certain administrators that have earned the trust of time. User's money is not stolen by banks that keep the record of the money held in private databases, so many users tend to choose centralized control for a reason. It also means that the institutions that have a control have to spend a significant amount of money to keep those centrally held databases safe from hackers and other types of theft.
Keeping the information
The majority of centralized databases keep the info which is up-to-date only at a certain moment, meaning that they actually have a snapshot of a certain moment. This is where Blockchain technology has a huge advantage. Blockchain databases can keep the info in real-time, and also have all the information that appeared in the past. Blockchain technology can create databases that have kept histories of themselves, which means that they constantly grow and expand archives of their histories while offering a real-time status.
Even though Blockchain can be used as a perfect system of record and is a very good solution as a transaction platform, it is still considered quite slow as database compared to the possibilities of a digital transaction system that PayPal and Visa offer.
While developers are constantly working on improving this performance, Blockchain technology still has to consider how to solve this speed sacrifice situation that is in its nature. Distributed networks in Blockchain tech do not share processing power, but they all independently operate on the network and compare the results of their work with other participants on the network until there's a match, confirming that the operation has been executed.
On the other hand, centralized databases are present and active for decades. They also had a chance to increase their general performance with a well-known recipe that comes in the form of Moore's Law.
Bitcoin is famous for being an uncontrolled database, which means that anyone can add a new block to the chain, and anyone is also able to read a block in the chain. However, a permission Blockchain, just like a centralized database, can be a controlled database, meaning that the network can be set up for only those who have permission to write blocks into the database or read them. So, when it's put this way, where confidentiality in the only aim, Blockchain database has no advantage over a centralized database.
To make some information confidential on the Blockchain network, a lot of cryptography needs to be done, which adds an extra burden to the nodes in the network. There is no easier way to do this than simply hiding the information completely in some private database that doesn't even need a network connection.
Depending on your needs, there's always one of those two systems that might be more suitable at the moment, but generally speaking, they both have different advantages and disadvantages.