The jacket font appears to be "Pump Bold" on Dallas, and "Pump Demibold" on Brett and Parker. Hard to be certain given the low quality photos I have at the moment. The Parker jacket was auctioned a few years ago tho I think...
Possibly some letters were tweaked manually to improve readability; to me the "S" looks more open for example. Or perhaps they used a different font from another manufacturer, or the letters could all be hand-drawn for all I know (ALIEN was made before the Mac came out! :lol)
A slightly lighter weight of Pump was used on the Moonbase Alpha patches seen in "Space 1999" (also a British production, and which used some of the same designers as ALIEN)
Pump Bold set tight is used for the nameplates on the Bridge stations and also the extravehicular space suits
(note the actual nameplate has some kind of design to the right of the name, but I approximated with a rectangle)
For the shoulder patch, Pump Light appears to be the primary font used on the USCSS NOSTROMO lettering. The letter "C" is more closed and could be from another font such as Futura.
The top bar on the "T" is longer on the patch version, and the "R" has a straight leg. So either this was hand-redrawn from Pump, or maybe there's another font out there that is substantially the same as Pump but from another manufacturer (as often happens).
The "U" and "N" are a bit wider on the patch than in the font (but this is the same letterform, and it could have just been drawn wider).
Gill Sans is a good match for the registry number.
Note that this supposedly production-used gray patch has a circular outline (it does not go to squared sides toward the bottom, like the blue patch which is more widely replicated).
Possibly the circular patch is a prototype, or maybe it's a smaller version made for the women's uniforms.
Patches used in the film also seem to be made from a lighter cloth than the fairly stiff replica patches made by Thinking Cap Company and others.
The registration number plate on the Nostromo miniature seems to use a weight of Futura, which is a font used commonly on vehicles in Gerry Anderson productions like Thunderbirds.
(and yes the registration number is different on the patches, on the ship model, and in the dialogue. :lol)
- k