I feel that arduino is for electronic enthusiasts who have spare money. If you are professional, it is difficult to learn the real skills with these electronic building blocks (circuit design, pcb layout, wiring, etc. are very important).
The other is that the cost is too high. The Raspberry Pi is biased towards embedded systems and is said to work well. I have to say it mainly depends on your interest. If you want to design embedded software, the Raspberry Pi is better (seems cheaper than mainstream embedded development boards, please verify ~). For embedded development, you need a team, and the underlying development is basically to modify other people's programs (off-the-shelf drivers such as LINUX, ANDROID are readily available, but I / O, ...:-|emmm.