NumPy excels at fast, memory-efficient numerical computations on homogeneous data arrays and is significantly faster for basic operations like arithmetic, slicing, and mean calculations, especially on smaller datasets (less than 50,000 rows).
Pandas provides user-friendly tools for tabular, heterogeneous data, supports complex operations (like groupby, merging, handling missing data), and allows more flexible data manipulation, but has more overhead resulting in slower performance for basic calculations compared to NumPy.
For large datasets (500,000 rows or more), Pandas can outperform NumPy for certain data operations due to internal optimizations; between 50,000 and 500,000 rows, performance differences are operation-dependent.
NumPy uses less memory and is optimal for machine learning model inputs, while Pandas is preferred for rich data analysis, data cleaning, and working directly with external sources like CSV or Excel files.
Indexing is faster in NumPy, while Pandas offers more advanced indexing and labeling but at the cost of speed.