Sort of Sears didn't actually manufacture anything, they just badged products made for them with a Sears brand name (Craftsman, Kenmore etc). They used a prefix to identify to identify the manufacturers, 101 is what they used for Atlas. Atlas made lots of things sold by Sears wood lathes, metal lathes, shapers etc. Typical number would be something like 101.21400 which would be one of several 6" lathes Atlas made for them over the years, 101 just tells you Atlas made it, the more important part is the number following the decimal, that gives you the specifics.
Although Atlas made them, in some cases there are some detail differences between the Atlas branded lathes and the Craftsman branded lathes, bearings and spindle thread on the 6" are the two main ones that can differ.
Sears sold several Atlas metal lathes in 6", 9" (very early) and 12" sizes.
From the cover it does appear to be one of the Atlas made lathes but it appears the head stock housing is missing which gives the odd appearance, or somebody put the cover on a different lathe. What I can see in your two photos though does look like whatever you have is at least based on a 6" Atlas / Craftsman lathe.