这两个句子的意思是一样的,都是：我昨天晚上听到狗在叫.但是语法结构不同
I heard dogs barked last night. 这是一个省略了that的宾语从句,相当于：I heard that dogs barked last night. 其中dogs barked last night是heard的宾语.
I heard dogs bark last night. 这个句子中,heard的宾语是dogs,bark last night是一个省略了to的不定式,作为dogs的宾语补足语
hear sb do sth是一个相当常用的句型：听到某人做某事,这里强调的是听到的结果,跟hear sb doing sth.要区别使用
同样的词还有：see feel等
I saw him step into the building. 我看到他走进这幢大楼.
I saw he stepped into the building.=I saw that he stepped into the building.