1)
Why does the Torah refer to the Melachah of the Chachmei-Leiv as 'Avodah'
1.
Ramban #1: Although the work was physical (Melachah), the Torah refers to it as 'Avodah', (which has spiritual connotations), 1 because they performed it in the service of Hashem.
2.
Ramban #2: It refers specifically to the Keilim, 2 to teach us that, they were careful to make even the Keilim precisely according to the specific instructions; whereas "Vayar Moshe es Kol ha'Melachah", mentioned in the next Pasuk, refers to the Mishkan in its entirety.
