How to compare two rows for variable data, using a formula

My table is as follows (although this is a sample, the actual table is 12Rx20C):

On the worksheet, there's also a list of all makers (named list MARKERLIST):

Both the order column and Markers columns are filled by a formula.

I'm trying to come up with a formula that fills in the 'Result' column. The following rules should apply:

• Adding a marker is not a problem, so NEG (so 50K to 601, marker B is added);
• When a marker is replaced, or dropped, that's a POS (601 to 97Y, marker A is dropped/ K3S to K12, marker F is dropped);
• Changing from one set of markers to another is a POS (95Y to M22 is a different set);
• Changing order, but keeping markers, is a NEG (M22 to K3S);

So far I've tried a COUNTIFs: =TRANSPOSE(COUNTIFS(B2:B4 , MARKERLIST) for all rows.Then applying a MAP function between two rows to find differences, along the lines of =MAP(COUNTIFS row 1, COUNTIFS row2, LAMBDA(a, b, IF(a>=b, 0, 1); which is then summed.

But this method gives a lot of false results, especially when a marker(set) appears multiple times in a row.

I tried to add in a SCAN function of the order list, to detect changes over there (one order always has the same marker set), but this still doesn't completely fix it. =SCAN(0, Ordercolumn, LAMBDA(a, b, IF(b = OFFSET(b, 1, 0), 1, "")

Preferably it would be done in a single column, but helper columns are allowed, although I'd like to keep them to a minimal.

I hope this makes sense, if anything is unclear, let me know and I'll try to edit in a better explanation.