Are they just different names for the same thing?

Yes Darren, in some parts of India, samosa is called Singara,

Singhara is actually a type of water chestnut that grows in ponds in India. It is traingular in shape, not unlike samosa. That is probably why some people call samosa singharas.

As waterchestnut, Singhara is quite delicious, crisp and milky. It can also be stir-fied into a bhaji. Flour made from mature singharas is used to makes various Indian breads and sweets, when people do not want to eat wheat and other cereals. I have only one recipe for it so far Singhara Halwa

Mamta

Here is a picture of Singhara plant and it's fruit:

http://www.survivaliq.com/survival/edible-and-medicinal-plants-water-chestnut.htm

This what the ponds where it grows look like: http://dnr.wi.gov/invasives/fact/wchestnut_photos.htm

When tender, the fruit is delicious raw. But matur fruit can be boiled and eeaten or made into a bhaji, just like potatoes.

Cooked (boiled) fruit http://www.fotosearch.com/CRT111/15323-09il

Mamta