I found this useful link - http://www.bryophyllum.com/b/articles/id/ and now I am able to identify the two bryophyllums that I have.
Number 1: Bryophyllum Houghton's Hybrid
My mother gave this plant to my son since he was so fascinated by it, and kept admiring it. He was taking good care of it, until he went off for his further studies, then the plant was left to my care.
Number 2 : Bryophyllum Crenatodaigremontianum
Believe it or not, I picked one of these plants of the pavement. There were a cluster of them growing along the pavement outside the row of shop houses. I thought they looked kind of interesting, so decided to plant them. When they were growing on the pavement, they were miniaturized, but I suppose in a more conducive environment like my garden, they have grown so big.
The Bryophyllums are actually easy to care for plants. Being succulent plants, they do not like excessive watering, and it is okay even if the soil dry up for a prolonged period. They are actually very tough plants despite their rather delicate look. They are alright either in direct or partial sun. No fertilizing is required. All they need is some watering now and then. They also propagate fast. Notice the plant-lets (rosette type small plants growing from the edges of the leaves) ? They will eventually drop and grow once on the ground. At times, assisted by the wind, they will disperse further from the mother plant and grow wherever there is a bit of soil. So far I have not seen them flower. Surprisingly they have rather shallow roots so they are really easy to pull out. I don't mind these plants growing anywhere they like in my garden .. lol !