"Ei sunt aproape de casa ta."

yes, both of them are used in the sense of ”close to”, ”near”, and they are mostly interchangeable. However, there are situations when one or the other may be preferred, like in enumerations, or when you want to stress the order (use lângă) or the distance (use aproape de). Ex: you put in order 10 forks on the table, you will say ”le așez una lângă alta”, which would stress the order, enumeration, but if you have only two and want to stress the fact that you put them VERY close to each other, you will say ”una aproape de cealaltă”. Spatially ”lângă” always mean very close (absolute), but ”aproape de” could mean any distance (relative). For example you go to visit a friend who lives 100 km away and he calls you when you are on the way at just 10 km away from his house, and asks you how it is going and how much longer you need, etc, you will reply ”ajung imediat sunt aproape de casa ta” (I will arrive at once, i am close to your house). Using ”lângă” here would mean that you are so close you can touch it with your hand, however, it can be used in figurative sense to stress that you are ”really close”.