Street lights used to be non-fluorescent with a transparent bulb that shines off in a yellowish color.
Some of these old street lights had a cup-like designed reflector; some others had a ruffle designed reflector that covered the bulb less.
The "ruffle" design are lifters that direct the light on to the street more efficiently.drios1
From looking at a few really old town pictures in an album at a library, it seems apparent in some way that the cup-like reflector ones once had a round glass shape covering the bulb.
The round glass is called a refractor. The refractor has prisms that distributes the light more evenly. It works in conjunction with the reflector.drios1
Purple fluorescent lights were common at some point since after they were installed. However, In the late 1980's, the brighter orange fluorescent lights became much more common as they began to replace both the purple fluorescent lights and the old-fashioned non-fluorescent ones.
I think that the purple flourescent lights you are talking about are actually Mercury Vapor lamps. I may be wrong though. I understand that floursecent lights were very popular up north. My experience has been in Texas. The orange lamps are High Pressure Sodium.drios1
Many fluorescent street lights also have stickers with numbers on them. They are yellow most of the time, but can also be white.
The yellow stickers are for High Pressure Sodium lamps. Blue stickers for Mercury Vapor (bluish-greenish white light); Red stickers for Metal Halide (white light).drios1
Numbers that I have seen on these stickers: 5; 7 (most common); 10; 15; 25; 40. One street light that I have seen has a less common X1 on its sticker.
The numbers on these stickers identify the wattage of the lamp. 5=50Watts; 7= 70Watts; the X1 is 1,000 Watts.drios1
Older street lights, including fluorescent ones, don't seem to have these number stickers.
A lot of problems with these stickers. They fall off or fade, maybe the white ones you've seen have faded.drios1
In many cases, when an old-fashioned non-fluorescent street light is replaced with a fluorescent one, so is its holder if it is one of those shorter, fancier-looking ones with the S-curve design. The replacement holder is usually one that is more streamlined and lengthier.
Modern luminaires "holders" are streamlined for wind loading. The less wind load the luminaire projects, the less loading the pole and the arm need to handle.drios1
On certain fluorescent street lights, there is an extra attachment. It can appear on either the front of the streetlight or the back. Perhaps it is for blocking some of the light coming from it.
The designs of a fluorescent street light have changed in subtle ways over the years. My guess is that the longer-looking ones are the earlier ones, perhaps dating at least as far back as the late 1960's.
As everything else, back in the 60's the luminaires were built to last a very long time. Bigger housings dissipated more heat. It allowed the internal components (ballast that actually operates the lamp) last much longer.drios1
Since 2003, the fluorescent street lights were redesigned as such as now not having a bulging glass cover. The glass covers on the brand new street lights are flat.
The refractor was replaced with a flat lens in order to eliminate the upward light component of the luminaire. This type of design will eventually improve the light pollution that prevents us from seeing the stars. This type of luminaire is called "cutoff". The inside reflector was modified to improve the light pattern but they are not as effecient as the refractor.drios1
Especially since 2007, I started seeing flat glass streetlights designed differently. The designs of streetlights probably change one every few years.
In Brattleboro, Vermont, there are some streetlights that have an unusual design. These are also fluorescent lights, but are much smaller looking. They are shaped like short cylinders.