Yes the attributes for those formats and electrical impulses were different.
I'd only seen one adapter that fit inside a standard size video cassette
recorder-player, for ungainly price, for a limited time. ~ It had electronics.
The other work-around, I have here between a few video appliances; to
use the patch cord from a working Hi8 Sony HandyCam to any other
conversion analog-digital device is the shorter path. I've also a two in one
unit that can be used to convert analog to digital and save that on DVD...
{Those have standard inputs: one need not start out with VHS to save to DVD.}
Once on DVD, the only problem may be the player may not see that format
if not suited to a usable standard in a computer or other type player... Once
the content is digital, one could use VLC or other graphic; if not iMovie.
Perhaps if your Digital8 vintage device isn't applicable, a pawnshop or sale
listing on craigslist may have second-hand unit, capable of the conversion.
Obsoletism is nearly a religion... To upgrade 'too quickly' without archival
means to retrieve vintage/obsolete nowadays may mean finding the retail
services of a small business who offers a conversion from one to another.
{Just like there are those who, for a price, will convert analog photo images.}
Sorry to have no solution to your issue; however this is a discussion...! 🙂