There are a number of definitions regarding "Blacked' and 'Spaded' from our perspective, most are interchangeable. But we consider a woman 'Spaded' when she receives a bare black cock and is subsequently inseminated. Same applies to the term 'Blacked'
However, we regard 'Spaded' as much more descriptive of what happens. The woman is never referred to as a 'Queen of Blacked' but 'Queen of Spades' Thus, the act of becoming a 'Queen of Spades' means that she has to be 'Spaded' In that regard, it's more of an 'action verb' than a more passive verb that 'Blacked' is.
Finally, when it's said that a woman is Blacked, the term is rather nebulas, especially when used among people that aren't familiar with the lifestyle terminology. But everyone get's the inference when it's said that she's been 'Spaded' We suppose it's more of an 'in your face' term whereas 'Blacked' is more passive.
That's out opinion but remember, opinions are like noses, everyone has one!