If when producing a product, part of the technology is the same as another company's patent, but the whole is different, is it considered infringement?

This depends on whether the same part of the technology is protected in the claims of the other party’s patent. If so, it is likely to be infringed.

For example, if the other party’s patent protects a sensor, and you use a sensor of the same design in a device, even though your final product is a device rather than a sensor, it is still infringing.