The Pre / EQ / Amp selectors (and the meters) are not present in the AT5 GUIs.
Many of the AT4 Amps have those 3 selectors.
But, have a look at 7.1/2 in the AT4 User Manuals:
Amp model / Pre model
This is the menu where you select your amp model. On legacy models, this will be labelled PRE MODEL instead, and will select only the preamp stage of the amplifier. On newer amp models, AMP MODEL selects the entire amplifier topology.
7.2 - Legacy model controls
Legacy AmpliTube amp models contain separate stages that can be individually selected. For these amps, the Amp module is divided into three separate models: Pre, EQ, and (Power) Amp. This allows you to design custom amps by choosing different components from a variety of amp models. The following controls are for that purpose, and are thus found only on the legacy amp models.
EQ model
This is where you select the EQ model in legacy amps.
EQ match
When EQ match is active, EQ models will automatically be matched to their Pre model counterparts by default when a new preamp model is loaded. Switching EQ match off defeats this, and the EQ model will not change when a new legacy Pre model is loaded.
Amp model
The final stage is the Amp model. Power amps from a variety of amp styles are available and are identified by their power tube type.
Now, AT5 has a separate effects loop, where the EQ can be added / changed. The AT4 Amp model selector (non-legacy gear) is the same as selecting a different Amp in the AT5 Browser, isn't it?