I claim no special knowledge of these. I do have accounts with two different power suppliers. The one serving my residence is a Co-op and they recently installed meters made by Landis+Gyr. Digital readout on what appears to be LCD. One of the co-op engineers told me that system would be fully operational in about 6 months. He says that the communication from/to the meter is on the 60Hz power line. Some systems, I am told, use radio signals.
The engineer says that this system does not notify the co-op of power outages. My imagination had suggested that a power outage, even of split second duration, would alert the POCO by a non-reading. That would be, my opinion, one of the major advantages to the customer of the smart meters. We have, on average, about one split-second outage per week, often while the Sun is shining and the wind is calm. Such outages are quite annoying and inconvenient. Unless notified, the POCO does not know of nor investigate
the cause of those outages.
I had also assumed that the system would permit remote disconnect of power for non-payment of bills or for other reasons. I feared that hackers could wreak havoc with that ability.
The other, investor-owned, POCO has a few meters that look to be smart meters. But not yet operational as such in this area. They are more sensitive to small current draws than are the old meters with rotary dials. On one vacant property, the controls for the gas furnace/AC were using about 2KWH per month while the property was vacant. The old meters would not register such draws if that was the only draw.
So apparently there are several different types of smart meters with differing capabilities.