Curculio glandium is often confused with another commonly occurring weevil of the same genera: the Nut Weevil, Curculio nucum, which lives on hazelnut trees.
In general, however, there are the following differences:
1. the lenght of the bulbous end of the antennae are twice the width in C. nucum (looks more bulky) and three times the width in C. glandium (looks more slender);
2. C. nucum usually shows a hairy "comb" on the vertical line on the back end of its shield which lacks in C. glandium;
3. the snout and legs of C. glandium are usually light whereas in C. nucum they are brown/black;
4. C. glandium usually lives on oak trees whreas C. nucum lives on hazelnut trees.

Caught in my self made moth trap.

1st, 2nd & 3rd photo: In my yard, Hilversum, The Netherlands, 19 August 2018
4th & 5th photo: In my yard, Hilversum, The Netherlands, 1 September 2019