Hi again and welcome to our STM32 World. We are here to help you :smiling_face_with_smiling_eyes:.
The STM32 eval boards have been designed as a complete demonstration and development platform for the STM32 MCUs and MPUs.They carry external circuitry, such as transceivers, sensors, memory interfaces, displays and many more. The evaluation boards can be considered as a reference design for application development.

The STM32 Nucleo are The highly affordable boards that allow anyone to try out new ideas and to create prototypes quickly with any STM32 MCU.Sharing the same connectors, STM32 Nucleo boards can easily be extended with many specialized application hardware add-ons (Nucleo-64 include Arduino Uno rev3 & ST morpho connectors, Nucleo-32 include Arduino Nano connectors).

Best Regards.
STTwo-32
To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.