Resistors on LCD - does a small difference matter? I recently have tried to connect an LCD to my Arduino Uno. The tutorial
tells me I need a 220 Ohm resistor, but the only ones I have are 330 Ohm. Does it matter?

Here's the Fritzing diagram by the way:
No, it doesn't matter. That resistor is just for the backlight LEDs. The larger the resistor the dimmer the backlight will be.  As @VE7JRO suggests, you can always put two 330Ω resistors in parallel, which will halve the resistance to 165Ω, which will give a brighter backlight.