Aguja wines are young, non-sparkling wines that must be consumed in the same year, in order to fully appreciate their freshness and the charm of their bubbles.
A "needle" wine is not a cava, nor a sparkling wine. It is one that, due to its varietal origin or its production, preserves a small amount of carbon dioxide from the fermentation of sugars. When you open a bottle, this gas is released in the form of a bubble, but without producing foam.

The grape varieties used to make sparkling wines are not special or different from other wines. If they are made from authorized grape varieties, that, due to the special practices of their production. For whites, it is common to find the same varieties as for cava (Macabeo, Parellada and Xarel.lo), while for rosés, Garnacha, Syrah, Tempranillo, Merlot, etc ... There are quite a few varieties with which make these wines. Sometimes the wine is sweeter and may have been made with Muscat grapes for example.

Sparkling wine can also be aerated. This occurs when part of the carbon dioxide contained in sparkling wine has been added.
In order to enjoy a sparkling wine well, it must be served at the right temperature, and this has to be strict in order to fully appreciate its freshness and the charm of its bubbles. Its service temperature between 6º and 8ºC. Sparkling wines are very fresh and fruity wines, they are very refreshing.

Source: catadelvino.com