The difference was in the frame materials, geometry and components. In general, the entry level models used plain gauge, CrMo main tubes with hi-tensile steel for the stays and forks. There were some entry level models with completely hi-tensile frames and in the mid-1980s some entry level models had triple butted MnMo main tubes. The top models would generally be butted CrMo main tubes with CrMo stays and forks. It could be double butted, tripled butted or splined triple butted main tubes, depending on the year.

Again, these are genralizations. To know the the exact composition would require a model name and year of manufacture.