Height Difference when growing different strains in one tent

Just raise the pots of the smaller plants to get them to the same level as the taller plants. Put them on saucers turned upside down or anything that wont absorb moisture.

some can catch up in flower during stretch, others may not... you can train the plants or use pot elevators/risers to even it out. I've been surprised by some smaller plants (in vege) that explode in flower, but not common. if it's bushy in vege it'll continue to be bushy later more times than not. Sometimes you want a known shorter stature plant going vertical before a lanky strain.. train the taller plant a week longer while letting teh shorter plant grow vertically a bit sooner... the lanky plant will catch up before the end.

I'd LST the taller plant. If it well outgrows the other in height then raise the smaller plant.