Alright, this question could be dumb...

[ojitos1985]

is there much difference between a F1 and F2 strain? I didnt know but i bought some nirvana´s seed and people talk about some F2, and for example, dutch passion are really more expensive and talking about F1, is there any F0 or something?

could be dumb you know but i really dont know anything about this just reading the internet and people talking about that F1 is really more potent.
¿Any1 here have compared, empirically, the potency of F1 with F2?

[Rusty Trichome]

I'm not the best to answer breeding q's, but I'll give it a go. (might even be helpful, lol.)
Here's a little strain-cross guide. This is done to stabilize desirable genetic traits in the next generation of seeds/plants. Selection of the donor plants (moms and dads) are key to this process, and are choices made from dozens (or hundreds) of seedlings/adolescents.

Better...? IDK... It is nice knowing exactly what phenotype you are to expect from a batch of seeds.

If female parent was an Indica, and the male was a Sativa...seeds likely will have at least 3 main expressions of the crossing.
One portion of the seeds will mostly take after the male, and grow like him, one portion of the seeds will be more short-n-squat, like mom...the rest will have various traits from both parents. Traits like more trichomes, skinny leaves but still squat, pithy stems, heavier stone, purple coloring...stuff like that.
The bitch looks to be growing enough of the plants out, to verify which traits you want to continue to develop and preserve, and then taking them all the way to seed maturity. This process can take loads of time and space.

Stinky...Do you by chance have a better chart showing back-crossing, too? It appears to be vaguely shown between the F2 and F3 germination, but not too sure.

Below is an example of a crossing:

[grey1223]

Don't worry about Nirvana's seeds. I've grown out about 6 or 7 of his strains with no problems. Also, I've found price is not indicative of quality. As far as potency it shouldn't matter if F1 or F2. F2's will vary and not be as consistent.

[stinkyattic]

I haven't seen a better chart- that one is good.
F1 should in theory be more predictable, since most breeders use select individuals and make the F1 generation breeding very repeatable.
F2 will have more variation among phenos. How much variation you see depends on how similar the original parents were. A pair of unrelated Afghanis will produce less variation when their offspring are interbred than an Afghani crossed against say a Haze, which is quite different in all aspects.