While they’re related to each other, they’re not the same thing.
They differ in important areas such as how they learn and how much human intervention they require.
While Machine Learning systems improve the more data they analyze, the most significant improvements require human intervention.

Lifewire
Examples of ML models include content and product recommendations based on “people like you.”
Because of this construction and specialization, Deep Learning systems are complex and often contain 100+ layers.
Instead, Deep Learning systems independently discover and define features in the data they analyze.
This example also helps demonstrate the correct applicability of technology to a task.
Deep Learning is better applied to more complex tasks.
FAQ
You don’t need to, but you probably do use them already.
It depends on the situation.