Hi Claire
on the 1841 all adult ages were rounded down so anyone aged from 15 to 19 is listed as age 15, anyone from 20 to 24 is shown as 20, etc. In addition:
The head of each household is not specifically identified, although he/she is normally the first person listed.
The relationship of each person to the head of the household is not stated.
Marital status is not shown.
Two small columns are used for place of birth instead of the one larger column in later censuses. The first states "Yes" or "No", often abbreviated to a single initial letter, to the question "Born in the same county?". The second indicates by an initial letter whether the person was "Born in Scotland, Ireland or Foreign Parts".
Kind Regards
Sue