as a result是具有副词词性的短语，在句中只能起过渡词使用，充当状语

而so一般作并列连词用，可以连接两个分句，构成并列句.

例如As a result， "Black" people are thought of as less competent and as having colder personalities.

There wasn't much traffic so we made good progress.

来往车辆不多，所以我们开得很快。