Ihave a an excel sheet that has 20,000 sku product id with poor descriptions. I have another spreadsheet that has updated descriptions that match the sku from the first sheet. I want to update the first sheet with the new descriptions from the other sheet.
The product skus are not in the same order on the two different sheets and the original sheet has other product sku's that will not have to be updated. Is their a good way to do this

I would use LOOKUP, VLOOKUP, or INDEX/MATCH to accomplish looking up the matching ID in one sheet to bring in the new description from the second sheet.

A basic index/match goes something like this.

Sheet2:
column A - SKUs in a different order
column B - better descriptions

Sheet1:
column A - SKUs
column B - bad desc
column C - this formula starting in C2

=IF(ISNUMBER(MATCH(A2, Sheet2!A:A, 0)), INDEX(Sheet2!B:B, MATCH(A2, Sheet2!A:A, 0)), B2)

Copy that formula all the way down the data set. Then highlight the new column, copy it, and EDIT > PASTE SPECIAL > VALUES to remove the formulas. Then delete the original column B.

All done. The formula given would preserve the original description if there is not a new one on the second sheet.

if you want to keep this in Excel I would go with JB's solution.

But it would be a lot easier to do in Access. You can link to the spreadsheet tables from Access then do a simple update query:

UPDATE oldtable INNER JOIN ON oldTable.SKU =newtable.SKU SET oldtable.Description = newtable.description;

If you need to do lookups on these products, Access will be easier.