At this age, a Toddler does not play interactively, they are still in the "parallel play" stage of development.
Look up the term, online.
Kids this age, do not know how to 'share' yet.
Kids this age, do not yet understand the full abstract meanings of social innuendo and social skills.
Kids this age, do not communicate articulately yet. Nor have the verbal skill to say everything, accurately. Nor do the know 'how' to express themselves. It is taught.
Kids this age, do not yet have, fully developed emotions yet. And they do not understand their emotions, nor have the words for it, yet. It is taught.
Boys are more physical.
Kids hit: when they are frustrated, tired, over-stimulated, or do not know how to express their wants or needs. Or when other kids, are irking them.
Kids this age: do not yet have, fully developed "impulse-control." They are reactors.
Kids this age, will also see what other kids are doing. But, they also get frustrated too.
They are also still learning, what is 'right' and 'wrong' and appropriate or inappropriate.
They are not yet at this age, articulate or cognizant of 'how' to react or what to do, when frustrated. ie: their level of "coping skills" are not developed yet. It has to be taught.
Kids this age, in a 'school' setting or with other kids, can sometimes just get overwhelmed. Because, they are so many other kids around.