Can someone please explain what a "de-SPAC" deal/how this differs to a "SPAC" deal?
The use of this in financial press is loose, so be mindful of how any given bit of commentary is written. But
A 'de-SPAC' refers specifically to the M&A deal whereby the SPAC takes on its previously private target co.; it's the consummation of the investment into an actual operating company, which then becomes listed (mechanics will vary somewhat).
A SPAC deal is often this, but can also mean the IPO of the SPAC itself.
In some cases, a 'SPAC deal' may also be in reference to the 'private investment in public equity' (PIPE) transactions often used to close out a de-SPAC; basically if the SPAC only has, say, $200mm but target value is $1bn, investment banks will underwrite or subscribe the remaining $800mm to close the deal in exchange for fresh equity which usually is issued shortly following close of the merger.
Again always be conscious of context because the writing can have a bit of slippage (though commentary on PIPEs will usually make it clear it's a PIPE). In any instance it should in most cases be clear what kind of transaction is being discussed.