Hi Dhruv!
Thanks for reaching out.
This difference isn’t so big to have what to explain so much in detail. Metrics are measures with business meanings attached.
However, a company will have so much data, that it could be able to produce hundreds or even thousands of metrics.
So, when presenting analyses to executives, it would be unnecessary to display thousands of metrics. That’s why one needs to pick those of them that are key.
Such metrics will be called key performance indicators.
For example, the Absenteeism rate is a metric. However, in the HR department of a firm, this metric is crucial for defining employee engagement in the work process. Therefore, the absenteeism rate of employoees normally  is also a KPI for the HR department of the company.
Hope this helps.
Best,
Martin