Maybe this history on the Shopsmith will help.
Shopsmith is the name given to the tool itself in 1947 with the invention of this 5 in 1 tool, the Shopsmith Model 10E. The inventor and his partners formed Magna Engineering Corporation to make the Shopsmith Model 10E and later it became the 10ER. The Shopsmith Mark 5 went on sale in March of 1954 and replaced the Model 10’s. The Special Purpose Tools (SPT) like the Jointer, Jig Saw, Belt Sander, etc. carried the Magna name not Shopsmith. Magna also made tools and parts for other companies. In 1955 the company split into two divisions. Magna Power Tool Corporation became the sales and marketing and Magna Engineering Corporation retained the design and manufacturing. In 1958 Magna Power Tool Corporation merged with Weber Engineering Products, Inc. to form a new company Yuba Power Products Inc. a division of Yuba Consolidated Industries who purchased the two companies. The Shopsmith/Magna line of tools still carried their Shopsmith or Magna names. YardSmith outdoor power tools were also made by Yuba Power Products. In 1962 Magna American Corporation was formed by a group of Yuba employees and continued the Shopsmith/Magna line of tools. Within a few years with dwindling interest in them they one by one discontinued making the different Shopsmith and Magna tools. In 1972 John Folkerth purchased the Shopsmith/Magna tool line and formed Shopsmith Inc. and restarted production of the Mark 5 and related tools but now the company name and the tool names were the same. Many of the Special Purpose Tools still carried Magna markings for several years but were now Shopsmith tools. When looking for Shopsmith tools or parts several names, Magna Engineering Corporation, Magna Power Tool Corporation, Yuba Power Products, Magna American Corporation, Shopsmith Inc. RLF Shop LLC and RLF Brands will be attached to them.
As for the differences Brenda covered most of it. The older Cast Iron Table uses the Miter from the Mark V for a fence as they can lock in the miter slot. The aluminum table has the fence as an option and the Miter can be used in the miter slot provided. Even the early 1950's Band Saws can be upgraded to all the current features. Something Shopsmith/Magna has always tried to engineer into there tools since the introduction of the Mark 5. Even the Model 10's were given options to add new accessories (the SPT adapter set you have). The only tool, more or less, left out of this up-grade ability was the old Mark VII. It can use the SPT's but most of the tool's components are made specifically for the Mark VII. The headstock is different but can be replaced by the Mark V headstock. The tables are a different size and other parts can be identified as from a Mark VII because they were cast differently. Example, the miter has a different lock and the tailstock has a different shape.
Mark V 520 S/N 09-11-01 completely upgraded to Mark 7, with all SPT's & more.
Model 10ER S/N R64000 first one I restored on bench w/ Shopsmith metal ends & retractable casters. Has Speed Changer, Model 4E Jointer, Jig Saw with lamp, a complete set of original accessories & much more.
Model 10E S/N 1077 oldest one I have restored. On bench w/ Shopsmith metal ends & retractable casters.