Is there any similarity between these two? How are they different?
Great to have you in the course and thanks for reaching out!
They are very different. The similar thing is that they both are tools for designing databases. However, the ER diagrams are more detailed and focus on the types of relationships even more as opposed to relational schemas.
On the other hand, the relational schemas deliver a lot of information on the database in a relatively simple and easily digestible way.
Then, learning both types of representations professionally can take you a lot of time. Weeks or months. Also, considering the differences mentioned above, ER diagrams and Relational Schemas differ visually, ER diagrams allowing for more detail when expressing relationships, and Relational Schemas being more ordered and clear to quickly understand which fields of the different tables are being related.
Hope this helps.