Maxi-size mega blocks are larger then duplo. As far as I can tell they have 2x the stud pitch and much larger studs.
What if-any compatibility is there between the maxi-sized mega blocks and either Lego elements or the smaller-sizes of Mega blocks.
Yes, maxi sided mega bloks are compatible with LEGO duplo and LEGO system pieces, but only if the duplo piece is 2x2 studs or larger or the LEGO piece is 4x4 or larger. Also, you can only connect LEGO system pieces and duplo pieces to the underside of maxi size mega bloks.