Starting your maker way you supposed to ask this somehow important question: Should I get an Arduino or a RaspberryPi?

So today we tried to find the answer from experts to know where better use an Arduino and where RasberryPi. The answer turns out to be simple and clear.

“Arduino uses a microcontroller; Raspberry Pi uses an applications processor. There are some things a Raspberry Pi is better for (you can hook a Raspi up to a TV, for example), and loads of things an Arduino is more suited to. There’s a good potential marriage between the Arduinos you might have in your drawer at home, and your Raspberry Pi, which you can use to drive them.” answered Harsh Kothari.   

“The Arduinos strength is I/O control while the Raspberry Pi is more a processing device that has the GPIO pins for I/O.  But the Raspberry Pi I/O connections are non-buffered and directly connect to the Broadcom chip, so if you make a mistake the chances are the chip will be fried.

For home automation Arduinos at the edge for actually switching relays and taking readings, with the Raspberry Pi centrally taking in the commands from the user, sending commands to the Arduino and taking feedback from the Arduinos to allow it to make decisions on what to do next.

A possible configuration is Arduino + Ethernet Shield with the various lights and sensors attached.

Raspberry Pi running a web server/control interface.

User connects to Raspberry Pi web interface. Makes selections and then over the network the Raspberry Pi sends the command to the specific Arduino that can then take the relevant action.

This configuration would play to the strengths of both platforms.” answered Albert Hickey.

Firstbuild.com even made an illustrative answer.