Greetings. After looking at your recent photos dated 1905 of Hong Kong's First Class and Third Class trams, I found this 1911 photo of a streetcar used in Regina, Saskatchewan, Canada. It must be of the same generation as the two in Hong Kong, given the similarity in their appearance and chassis. This one, or at least the heavy machinery part, likely came from the same factory in Britain.
The Regina streetcar is longer with a bigger seating capacity, has door opening on the right side given that people there drive and stop on the right side of the road. It also has a coal stove inside to keep passengers comfortable if not warm, as temperature here in winter can drop to -40 degrees C, which I experienced while living there. By the time I settled in Regina in 1964, they have retired these streetcars, and began using buses connected to overhead likely the same trolley wires.
1905 Third Class HK tram - https://gwulo.com/atom/32911
Reference - https://gwulo.com/tram-timeline
Regards, Peter