我要清点Pig的数量

transactions = LOAD '/user/valivetv/transactions.csv' using PigStorage(',') as (transaction_id:long,transaction_date:datetime, cust_id:long, age:chararray, area:chararray, prod_subclass:int, prod_id:long, amt:int, asset:int, sales_price:int, phone_no:chararray, country_code:chararray);
data_grpd = GROUP transactions ALL;
string_stats = FOREACH data_grpd GENERATE  group,COUNT_STAR(transactions.country_code),COUNT(transactions.country_code);
string_stats1 = FOREACH data_grpd GENERATE  group,COUNT_STAR(transactions),COUNT(transactions);

我注意到string_stats和string_stat1都给出了相同的输出。
count（交易。国家代码）和count（交易）之间有什么区别？