The Arduino is based on hardware, which means you won’t get far without some components: LEDs, LCDs, resistors, motors and the like, depending on what project you want to do. You need no experience or components (other than a monitor, keyboard and mouse, which you have right?) to get the Raspberry Pi to do something. Just plug and play!
If you want to make a hardware project then the Arduino is by far the best choice. The analog inputs and PWM outputs add a whole spectrum of compatibility the Pi cannot do natively. Plus the large about of I/O pins let you connect multiple sensors and feedback components. The Arduino however is not as powerful as the Pi, so there’s no proper audio, video or internet out-of-the-box (you can however add basic functionality of this). The Arduino can send data to your PC or Pi, over serial, and you can then create a program to read this data and do something.
If you want to make a software project then the Pi is the way to go. The audio, video and internet capabilities make it the winner in this aspect. There’s no need to attach external components, so there’s no real need to learn electronics.