SIMATIC Markup Language (SimaticML) is a Siemens standard based on XML for the exchange of software data in TIA Portal. The standard is used by TIA Portal Openness when exporting and importing software data such as program blocks or HMI screens.
REF: (Siemens industry)
Automation Markup Language (AML) is an open standard based on XML for exchanging hardware (CAx) data. The CAx data import in TIA Portal uses TIA Portal Openness to generate the hardware configuration and networks.
REF: AutomationML
You can find further documentation and help in the following links: