the coefficients of gI are much smaller in M2 in comparison to Singular:
R = QQ[x,y, MonomialOrder=>Lex]
I = ideal{18*x^6+19*x^4*y-22*x^2*y^2+20*x*y^4-24*x*y,-18*x^6-28*x^4*y^2+5*x^3*y^3+24*x^2*y^3-15};
gI = gens gb I
toString gI
gI % I
(gens I) % gI
the coefficients of gI are much smaller in M2 in comparison to Singular: