Slow growing girl (right)

Different strains.........different growth patterns! They are both on the fourth set of leaves, so they are actually growing at the same rate, despite the size difference. Don't worry, they will be fine.

Every seed is potentially different, even if it has the same parents. All other things ignored, i'd wager the faster growing plant is an F1. F1 hybrids are generally more robust/vigorous. But, just because it's the best odds, doesn't gaurantee anything. if consistency is supremely important, grow from clones. Seed will always come with variety - some good, some bad. The more inbred an outcropping plant is, the more negatively impacted the growth is, but if you have a clone of a plant that is known to be vigorous, none of that matters as you already now the phenotype that will result with competent methods. An s1 can be a vigorous plant, but won't be as often as an F1. thinkit's come up with your other questions -- fix your irrigation habits. They look suspect. Also, add more perlite or similar to your medium. a coco base should be 1/3rd perlite or similar. A sphagnum peat moss bas should be 1/2. This is relative to expected water capacity.. in the end both will have a similar gas:water mixture in the medium. This is why it's a total myth that coco is somehow better in this regard when both can attain the optimal target and both need drainage elements added. Even if doing everything as best as possible - not that that knowledge is 100% mapped out for this species - you will still have a good deal of genetic diversity. While not normal in the marijuana cult subsect of gardening, you typically plant more than you need so you can throw out defective and or mutated outcomes. If growing from seed, this can greatly improve consistency of outcomes, but what you can se with your eye early on certainly isn't 100% able to predict future outcomes. It merely improves consistency a noticable amount. Sometimes this is cost-prohibitive when breeders have a 20,000% profit margin.

They are good they look Healthy and the size is correct for there age. Chill brother watch them grow

They're looking ok, although maybe asking for a little more nitrogen in their feed? The next week they should really take off. How much light are they both getting?

hey 👋 For 17 days, your two plants seem to be on the right track and in great health 👌 In about a week, you can start LST ; with two plants, you’ve got enough space in your tent to spread out their canopy. As for knowing which one is which, you’ll have to wait until the buds appear 😉