The different strains theoretically mean a specific average genome, and that means a certain signature of plant - but it's pretty complex. Certainly not a case where the same strain = the exact same genome, but with less variability there is some sense that the same strain, from anywhere, should carry much of the same chemical constituents once harvested, and therefore the efficacy should largely be similar.
I've got some buds off one plant of Chocolate Poison that matured purple, whilst I just finished an Oz of the same seed stock (same mother plant) that was green. Both were grown geographically far apart in slightly different climates. A lot of the signature carries through, it's notably different to the Caramel Poison grown with it - having different flavour (terpenes, flavonoids [hundreds of variants possible]), different potency (dissimilar cannabinoid spectrum [~135 variants possible]).
But the flavour and effect between the two different Choc Poison buds is obviously similar despite the colour, so the variance to the constituents between them is very similar, though the appearance is not. Given how far south I live, the fact the green plant was grown in a coastal location compared to elevated and inland, and with the timing between harvests - the more mature inland purple plant would have been exposed to colder temps overall and for longer, and I have seen this procure purple harvests before, and would note that frostbite can produce this discolouration. (and note that a strain like Granddaddy Purple, is a whole different shade of purple, and much more marvellous! - but googling it shows green pics, not like the near-black leaf plant I sampled..).
Interestingly, anthocyanins - the pigments that might cause the purple hue - are flavonoids, and so would generally be vaped even at low temps (but also dwindled in the curing process, as with chlorophyll (green pigment)).
I'll have to get some more green choc poison to directly compare. But the colour alone does mean that the chemical constituents are not exactly the same.
From what I understand, there is an entourage effect between the terpenes, flavonoids and cannabinoids which impacts how we biochemically interact with them. And so I find it makes sense that if the strain is the same, then the effects should be quite similar but never identical.
But also, when it comes to cannabinoids, I think it's a very manipulative experience. It is a psychedelic experience, and so set and setting really can influence the effect more than the exact chemical composition of a dose. Police interaction is something that comes to mind that can quickly disrupt a feeling of bliss. And anxious sensations can't always arrive if the environment disallows.
I've had effects from just cannabis ranging from decent hallucinations, visual and auditory, even blindness, as well as strong euphoria, or paranoia and slight discomfort, lockjaw, cotton-mouth, energetic stimulation, uncontrollable sedation, but mostly just a nice sense of calm, very rarely a mild anxious panic.
If you read up on a strain before you try it, and then consume it with some expectation, that is likely going to cause a slightly different interpretation of the actual effects. It's a bit like a horoscope, the descriptions are already open for interpretation and don't necessarily define anything.
However the actual science that exists behind many of the medical strains is not baseless.
Jack Herer is a good starting point into the world of cannabis strains.
"Created in the Netherlands in the mid-1990s, where it was later distributed by Dutch pharmacies as a recognised medical-grade strain. Since then, the
spicy,
pine-scented sativa has taken home numerous awards for its quality and potency. Many breeders have attempted to cultivate this staple strain themselves in sunny or Mediterranean climates, and indoor growers should wait 50 to 70 days for Jack Herer to flower."
One of the terpenes, Beta-Caryophyllene, in that strain, and many like Blue Dream (lots of the crowd favourites actually), is also found in black pepper, you can find anecdotal evidence to suggest that chewing black pepper whilst suffering an uncomfortable THC high can mellow the intensity.
However if you can source good buds that already contain the active chemical, maybe you'd be two steps ahead.
One thing humanity has taken for granted for the longest time, in a crucial period I suppose, is the complexity of the clandestine lab that the cannabis plant is. For so long, since the 1920's, we have been synthesising all sorts of problems and banished the solution.
Synthesised cannabinoids are incredible, and really can display the vast potentials with the ECS. However consuming the research chemicals provides good evidence to suggest that there is a large part of the puzzle missing or neglected. As cannabis is properly in the mainstream nowadays, there's a lot of insight documented as to why homogeneous drugs don't work as well, and what it shows is that strains are really more important than we could ever realise. Full plant spectrum exposure is the better choice that doctors are, and will be, discovering, and recreational users already understand. And in order to obtain the best spectrum, nature is so far ahead as to be unsurpassable.
How much we actually know means that strains are less important than healthy plant access, as every plant is it's own little galaxy that exceeds feasible testing limits. But knowing a strain means you can better understand what to expect. If you want to avoid a particular flavour, you can easily do so by getting something that has a closer profile to what you want or require. Beyond making it go down easier and being more enjoyable overall, it changes how it impacts you.
Better cannabis makes more than a small difference. No one should be a strain snob, but every stoner needs to understand that strains do matter, and they have the capacity to mean different things to different users.