The difference is:

Trademark refers to: (registered) trademark; (human behavior or clothing) characteristics, marks.

Brand refers to: trademark, brand; brand; stigma, shame.

Example sentence analysis:

trademark

1. The designer bars which have become the new trademark of the city.

Have become this A fashionable bar with a new logo in the city

2. The trademark is registered on the book of the Patent Office.

The trademark has been registered at the Patent Office.

3. Please identify the registered trademark.

Please identify the registered trademark.

brand

1. I bought one of the leading brands.

I bought one of several best-selling brands.

2. Advertising agencies are losing their once-powerful grip on brand marketing.

Advertising agencies are gradually losing their once-powerful grip on brand marketing.

3. In office supplies, we're the brand leader.

Our products are the leading brand of office supplies.