Yes, there really is a difference. There are MANY wines that "sparkle", but the rule of thumb is this.... Champagne comes only from the Champagne region of France; Prosecco, Mostaco di'Asti and Spumante hail from Italy; Cava is made in Spain; Sekt is a product of Germany and "Sparkling Wine" can come from anywhere.
It sounds like snobbery but each one of these sparklers are different. Here is a quick and dirty explanation of some of the differences.
The famous Champagne has a different mouth feel... The bubbles are much finer in texture than say... Oh, Prosecco from Italy which has more of a "soda" sized bubble. And while Moscato di' Asti has very fine bubble-age, it tends to be much sweeter and have slightly less carbonation (frizzante) than say a Cava from Spain. And while there are Sec (sweet) Cavas, they are usually much bubblier. Then there is "Spumante" which is super bubbly and also tends to be a little on the sweeter side than your typical Prosecco.
The reason for this is a difference in method... Champagne undergoes it's secondary fermentation in the bottle, while Prosecco is fermented in stainless steel tanks. Sekt uses the "Champagne Method" or "méthode traditionnelle" but uses different grapes with difference sugar content, thus a different end result.
Which brings me to the big difference, the grapes.... Champagne is typically a mixture of Chardonnay, Pinot Noir and Pinot Meunier (unless it's a Blanc de Blanc in which case it is ALL chardonnay); Prosecco is produced from Glera grapes while Moscato di'Asti and Asti Spumante are manufactured from Moscato Bianco grapes; Cava is formed of a mix of Macabeu, Parellada, Xarel·lo, Pinot noir, and Subirat with Chardonnay being a recent addition to the mix; The Sekt, in Germany, which while fermented by the traditional method of Champagne, is constructed of Riesling, Pinot blanc, Pinot gris and Pinot noir grapes.
Whew! And that my friends, is just the tip of the iceberg when it comes to sparkling wine.
Now that I have thoroughly bored everyone to tears... I am not using Champagne, Sekt, Prosecco, Moscato si'Asti, Spumante, Cava nor a Crémant or Mousseux (Sparkling wines from France, but not from Champagne), I am simply using a Sparkling Wine from California. LOL
Thus this is not a Kir Royal (Créme de Cassis & Champagne) but a Kir Pétillant (Créme de Cassis & any Sparkling wine), though even THAT is incorrect.
When I make a Kir Pétillant I prefer to hybridize it a little with the deliciousness of a standard "Champagne cocktail", with it's Angostura laced sugar cube. Thus I am able to enjoy not only the, now, effervescent fruitiness of the Creme de Cassis, but also the subtle spiciness of the Angostura Bitters...
It's Heaven in a flute. Then again, anything that contains currant is heaven.
Kir Pétillant Cocktail
Sparkling Wine (Extra Dry)
2 tsp Créme de Cassi
a twist of Lemon Zest