The phrase "different storylines" refers to multiple parallel narratives or plotlines that exist separately or intertwine within a larger story. Full definition
There are several different storylines in this that all come together in the end. (puppiesandpretties.com)
Players get to choose which girl they want to date (although certain choices are locked at first), so they'll see different storylines depending on who they chose to romance. (playstationlifestyle.net)
The characters are too often on their own island, as when a soap opera cuts from a close up of one deep sigh to a completely different storyline. (maddwolf.com)