The differences in 'healthiness' between types of sugars are relatively negligible (except for agave nectar which has the lowest glycaemic response). Otherwise it is more a matter of the taste.
These can include anything from brown sugar, agave, palm sugar and demerara, among others. Although the use of some sugars has also shown some beneficial health effects (such as the use of honey on wounds), these are predominately due to their antimicrobial and antioxidant activity where products assist in cell regeneration.
It is true that some sugars are sweeter than others, which affects how much is used. Nevertheless, our body will still treat the sugar as sugar, regardless of the type.
In the supermarket, there are a limited number of products that do not contain at least one form of sugar. This can be part of natural foods such as fruits and vegetables, or added to products such as cereals.
The 'hidden' sugars in food are there for a range of reasons. In some cases, has to be added to make the product palatable.
White sugar for baking cakes helps the mixture distribute evenly, without interfering with colour beyond the expected caramelisation. In other cases, sugar is added to food to extend its shelf life (jams, for example).
Considering sugar is present in fruits and vegetables, its consumption has been questioned relatively recently. For example, a zoo in Melbourne stopped feeding their animals fruit as it was shown to rot their teeth.
However, animals and human are obviously different, and this would probably also occur in humans if not for our superior dental hygiene.
Several studies have shown that consumption of fruit is beneficial for health beyond the sugars they contain. Fruits contain a wide range of nutrients (including sugars), bioactive compounds, vitamins and minerals. The amounts of each one of these will vary between the types of fruits, seasons and also the stage of ripeness.
Importantly, this is not the same for products such as fruit juices. This is because one glass contains the juice of several pieces of fruit. Eating whole fruit, therefore, is much better for health rather than drinking juice.
The negative consequences of excess sugar are well shown in current scientific literature. These include the potential causes of obesity, chronic disease and death. It is also implicated in changing gut microbiota and addictive behaviours.