arduino ide生成的两个hex文件有什么区别吗？

只能从名字区分

一个是标准固件，bootloader是底层固件

如果下载到单片机上用哪一个呢？

         2楼说得对

不带bootloader的      

想问，如果编程的时候，Arduino里面有库文件，和自己改的库文件，生成的HEX文件还是可以正常仿真的吗？

引用https://forum.arduino.cc/t/uno-s ... n-meanings/409517/3上的回答：
As the names indicate, the first doesn't include the bootloader, the second does. When you do a normal serial upload over USB to an Arduino the bootloader receives the serial communications and writes the sketch data to the flash memory. Normally when you upload a sketch to your Arduino using a programmer the bootloader is overwritten by the sketch so you can no longer do serial uploads via USB until you have burned the bootloader to your Arduino again. However, if you upload the with_bootloader hex file then the bootloader and sketch will be written to your Arduino and you will still be able to do serial uploads.
正如名称所示，第一个不包括引导加载程序，第二个包括。当你通过USB向Arduino进行正常的串行上传时，引导加载程序会接收串行通信并将草图数据写入闪存。通常，当您使用编程器将草图上传到Arduino时，引导加载程序会被草图覆盖，因此在将引导加载程序再次烧录到Arduino之前，您无法再通过USB进行串行上传。但是，如果你上传with_bootloader十六进制文件，那么引导加载程序和草图将被写入你的Arduino，你仍然可以进行串行上传。