In French, the two categories are distinguished:
http://www.worldhotelrating.com/guidelines.php?sv=253The difference between "hotel de charme" and "boutique hotel" ought to be that the former are small, exclusive, extra-urban and preferably historic and while the latter are small, exclusive, urban and distinctive but if you google for Italian examples of both, you will see that the categories overlap considerably. "Boutique hotel" is more widely used in English so whether you go for that or "hotel de charme" French option will depend on your audience.
Or you could cover all the bases with something like "boutique-style 'hôtel de charme'".