Got to the image. That's not a boa. That's a reticulated python. The image even says huge python. The world's longest ever recorded snake in captivity was a 27 foot reticulated python. A boa constrictor does NOT get that big, unless you count the anaconda.
But this. A boa constrictor imperator.
Will get to MAYBE 10 feet.. If it's a large female. 14 or so has been recorded, extremely rarely and at an astounding age of at least 30 years old. Average is 7-9 feet.
Are specifically the largest snakes you'll ever find. The anaconda, the burmese python, and the reticulated python. They reach an average of 18 feet, but have been known to get larger. 27 feet was the longest ever seen.
The difference is like an arrowana vs. an arapaima...both are big..But one is not as big as the other!