Morning!
I think that parcels sent light packet have to fit through the "slot of doom" at the post office...(be less than 2cm thick?) I could be wrong, but I think it's just a step up from letter mail....
Small Packet is pretty affordable, and usually pretty quick, I have had good experiences with it! Again, I I think there is a weight limit, before you are bumped up to premium shipping....It's always available as an option if you ship online, but be careful if you are buying postage at the PO, they never offer this choice (to me anyways) they always try to suggest Expedited Parcel instead, I have to ask for Small Packet if I buy postage there, haha, one lady didn't even know it was an option!! :)
both are good options, imo, I am just feeling jaded with Canada Post and their crazy prices today!! :)