Summary
If the text file contains tabular data, the Describe function returns the Table and Dataset property groups for text files; otherwise, refer to the File property group.
For a text file, the Describe dataType property returns a value of "TextFile".
Code sample
The following stand-alone script displays some text file properties for a text file that has tabular data:
import arcpy
# Create a Describe object from the text file.
#
desc = arcpy.Describe("C:/data/evac_table.txt")
# Print some table properties
#
print("HasOID: " + str(desc.hasOID))
print("\nField names:")
for field in desc.fields:
print(" " + field.name)