Futanari are different from trans. For true hermaphrodites, if they have visibly open vaginas, they don't have scrotum, aka balls. But they can have penis. For trans, they absolutely don't have open vaginas and can only have chopped off balls. That means Futanari look like 75% women.
There really isn't an accepted, widespread definition of various intergender terms in fiction. Some of which are considered insulting outside the fetish community, but there really aren't any accepted alternatives.
That said, 'futanari' literally means 'hermaphrodite'. True hermaphrodites are
really rare and generally only occur among invertebrates and fish. That said, synchronous hermaphrodites have to be able to produce both sperm and ova, so it doesn't make sense to have a human-complexity 'herm' without balls, to me.
A male to female transgender can certainly have an 'open vagina'. That's what a vaginoplasty is for. They don't just 'cut off balls'. It's an incredibly delicate operation that takes at least seven hours of surgery. But when it's done well, a non-doctor can't visibly tell the difference between a surgically constructed vagina and a natural one.
All of which is a really long-winded way to say, 'futas' can have balls or not, and show up both ways in art and comics. 'True hermaphrodites' are incredibly rare in the Real World, but generally have both sets of bits in art I've seen. And I know a lot of trans people who haven't had any surgery, and thus still have a biologically male package, or have had 'bottom surgery' and appear fully female, but I don't know any who've had an orchiectomy.
TL;DR: You can like what you like, let me like what I like, and get off to whatever floats your boat.
Edit: As a ponderment, has anyone done a game with series hermaphrodites? Female becoming male, or male becoming female, or even swapping back and forth? One-way gender swaps are more common in nature than synchronous hermaphroditism, and repeated bidirectional seems to be the rarest.