The problem is the comentarial/Abidhammic notion of samatha jhana. Acording to this notion, during jhana the senses are shuted down and there is singleness of mind. But that's not what the suttas say. In MN111 for example, you can see that that's not the case.
The Mahasi/U Pandita tradition is very traditional (in the sense of accepting and folowing the Abidhamma and comentaries), but also very based on experience. So they found these concetrated states of mind similar to the jhanas as taught by the Buddha (the "sutta jhanas"). Since these states of mind don't fit the traditional samatha jhanas defenition, they called it vipassana jhanas.
In conclusion, the vipassana jhanas are the sutta jhanas aplied to vipassana.
He turns his mind away from those phenomena, and having done so, inclines his mind to the property of deathlessness: 'This is peace, this is exquisite — the resolution of all fabrications; the relinquishment of all acquisitions; the ending of craving; dispassion; cessation; Unbinding.'
(Jhana Sutta - Thanissaro Bhikkhu translation)