The use of Discrete fan or Integrated fan is based on how graphics is handled by your system. Discrete fan is used on models that have dedicated graphics card and Integrated fan is used on models that have integrated graphics.
The picture on the right(Source:Lenovo Support) shows both Discrete and Integrated fan for use on Lenovo Thinkpad T410 and T410s. As can be noticed, the discrete fan has two seperate heat sink plates and heat pipe running to the fan. The larger plate aids in cooling the CPU and the smaller plate aids cooling the GPU(dedicated graphics). The integrated fan has only one heatsink plate i.e., for the processor.
These fans are not interchangeable even though they both belong to T410. While gettings a replacement fan, you should consider the one that is appropriate for your laptop based on whether you have Discrete or Integrated graphics on your system.
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