I was wondering since im doing a school project if I can use arduino nano to control leds or I have to buy arduino uno to do it.
And what is the difference between using one or the other since I wanna make diffrent light effects and have it power on and change effects with mobile device
The UNO is a rather inconvenient device to actually use. If you have a "shield" that fits it, and that fulfils your whole project, then it is useful.
Otherwise, the Nano which can be mounted on a "solderless breadboard" for prototyping (which a UNO cannot due to its pin arrangement) or stripboard or a custom-made PCB onto which it would socket or attach, is a vastly more practical module, so you have the right one already.
They are functionally identical except for two things: The 16U2 USB interface chip on the UNO can be programmed to do something different - but this is extremely rarely appropriate - and it has a buffer on pin 13 so that the "L" indicator LED does not pull it down. If not specified in the sketch and not connected to anything, pin 13 will float and the "L" LED may flicker.
Actually, the Nano has two more but analog-input-only pins than the UNO due to use of the SMD chip.
Power it from the USB port or the "5V" pin with a regulated 5 V supply - such as a "phone charger", do not use "Vin".
Noted your intention to control it from a mobile phone. That will get complicated, will probably require a Bluetooth board.
I have used a Nano for controlling 50 WS2812b LEDs with success. If you wonder, it's a xmas tree decoration project.
A picture of the box. Note that the Nano board was not been installed when I took the picture.
Update: I got an error while trying to add the image, so you can see it here
Cute how you wedged the power supply in. No ventilation however, hope it was substantially over-rated.
The box has been in operation for a month. If I lay my hand on it, I can hardly feel any heat from it. It's a 3A 5A power but since the LEDs is using levels up to 80-90 (of 255), the power consumption is not that big.
Notice the prototype PCB at the side of the box. It's contain resistors. I used a double-sided adhesive tape to fasten it to the box.
When I had assembled the box and tested it against a different WS2812b led strip, I had a small accident. The led strip has extra wires for power supply and both 5V and GND was unprotected. And what should not happen happened - the two wires short circuit and the power blow. Took me an hour do disassemble the box and replace it while my wife could hear "D*m fc...." and other words not suitable here 
thehardwareman:
I have used a Nano for controlling 50 WS2812b LEDs with success. If you wonder, it's a xmas tree decoration project.A picture of the box. Note that the Nano board was not been installed when I took the picture.
Update: I got an error while trying to add the image, so you can see it here
Only 50? My 5-ft tree took 350 LEDS.
Nice case, where did you get it?
Electrical supplier I would guess.
Yes, only 50. That's because the xmas tree is small. I have had it at my office before Xmas and home during Xmas.
The case and all the other things are bought from Ali Express (my global hardware pusher ;))
BTW, I wanted to attach an image of it, but also this time I get an error message that it is not possible, so I put it on my webserver (also home made of cause).
You can see it here
