Is hydrogen bonding in ethylene glycol stronger than in ethanol?

The difference in hydrogen bonding between ethanol and ethylene glycol is not so much in the strength of the hydrogen bonding as it is in the number of hydrogen bonds each molecule can form with other molecules.

The strengths of the individual hydrogen bonds formed in ethylene glycol and ethanol are roughly the same. However, ethanol only has one -O-H group, whereas ethylene glycol has two;-

Ethanol

Ethylene glycol

Therefore each molecule of ethylene glycol can form twice as many hydrogen bonds with other molecules as those of ethanol. This effect can be seen in the boiling points of the two liquids;-

Ethanol b.p. 78.5 °C

Ethylene glycol b.p. 197.3 °C

Viscosity is another property that is affected by hydrogen bonding. Substances which are able to form hydrogen bonds tend to have a higher viscosity than those that do not, and substances which are able to form multiple hydrogen bonds exhibit even higher viscosities.

This is demonstrated by the very different viscosities of ethanol and ethylene glycol;-

Ethanol, viscosity = 1.1 cP (at 25°C)

Ethylene glycol, viscosity = 16.9 cP (at 25°C)