Microlight / Group A
The Ikarus with the extra fuel pump would be a category A light aircraft equivelant to a Cessna 150 or summat similar. Suspect it would be authorised to fly at a higher MAUW and thence have a greater range/payload combination.
Microlight aircraft (UK) current definition:
No more than two seats with max weight limitations as follows
a) 450kg for a 2 seat landplane
b) 495kg for a 2 seat amphibian/floatplane
Wing loading: Not to exceed 25kg sq.m
Stall speed: Not exceeding airspeed of 35knots/41mph
There are a number of excellent designs in the microlight category. Some of them are able to be flown at greater all up weights in other jurisdictions.
In the UK these aircraft are issued permits to fly via either PFA or BMAA
EDIT: Apologies to Whopity, you were quicker on the keys mate.