"on a different line" is correct and can be used in written English.
An example of its use would be: "I wrote her name on a different line."
Are we going on a different line?
Others drive to Manhasset, which is on a different line.
You have to try it a couple of times or perhaps I will play left wing on a different line.
"The point is that the ball went into the water on a different line to when it first crossed the hazard as it deflected after hitting the pin.
The couple, with their two young sons in tow, had the same luck on a different line last weekend, en route home from the Bronx Zoo.
Some residents drive to Ronkonkoma, on a different line, where rides are as short as 66 minutes and most are direct.
Just a few years ago, Copeland might have stopped Taylor on a Southeast street corner for a different line of questioning.
Now, press Enter on your keyboard to switch to a different line.
Get out at your stop or, if A and B are on different coloured lines, the station where you need change to a different line.
The research that The Guardian was commenting on used a different line of evidence: reductions in the size of molars, unrelated to reduction in general body size.
Richard Leonard has caused further confusion over Labour's position on Brexit by taking a different line from Jeremy Corbyn on membership of the customs union.
