I've used greyhound many times. They are faster than Canada Post ground. And usually cheaper for enormous packages. But only to places they travel, of course. Look up greyhound courier. But depending on what you're sending (weight, size, destination), it may not be the cheapest.
Canada Post has 3 forms of mail (one is a courier), and depending on the size, weight, and destination, they vary in price, so that it sometimes is even cheaper to send things via their faster methods than the slow way.