1)
What labor do they do in the field?
1.
'Rashi': They dug and pruned.
2)
What did Shim'i and Zavdi do?
1.
Radak: Shim'i was appointed over gathering the grapes. Zavdi was appointed over the vineyards at the time of gathering Peros and grapes from the time of the grape harvest and onwards - "l'Otzros ha'Yayin."
2.
Malbim: Shim'i was appointed over working the vineyards. Zavdi was appointed over gathering the produce of the vineyards.
