I was looking up my family’s lineage and came across a family crest. The crest is for the Bullock family. Wiki says the family is English, but when you look up the family crest, you can find a Scottish and an English crest that have only two real differences. Why are the crests so similar? Did the family branch off to the two different countries, and just use the same crest? Any advice or knowledge is greatly appreciated. Thank you, so much.
First, it's important to point out that, under British heraldry, there is no such thing as a "family" coat of arms. A coat of arms is legal property belonging to an individual and using the coat of arms of someone else could be seen as a kind of impersonation.
As a courtesy, the nuclear family members of the owner of a coat of arms could display his arms as their own, but only with additions made called brisures which marked out who they were in relation the original owner. For example, a wife could use her husbands coat of arms as long as a lozenge (diamond shaped symbol) was added to it. The first son could display his father's coat of arms with a label of three points along the top. In England this system was not always carefully observed, but it was strictly enforced in Scotland.
Now for crests. Crest are not synonymous with "coat of arms". The crest is a symbol worn on top of a helmet (at one time on top of real helmets, but usually just in pictures). Like the coat of arms itself, the crest was officially granted to the bearer and the use of it by someone who didn't own it was not allowed. But, the crest could be put on a badge and this badge could be worn by anyone associated with the owner. This has probably had something to do with the erroneous use of "crest" to mean "family coat of arms."
As for your question specifically, most of the time when you look up a "family" coat of arms online you get services who are trying to sell you products with said coat of arms on them. What they do is look up anyone who had a coat of arms who shares the same last name as you (whether you are actually related to that person or not is irrelevant) and present you with that individual's arms. So the arms you are seeing as Scottish, which have an "argent" (silver/white) chevron (V-shaped mark) are the older coat of arms, originally the arms of Thomas Bullock of Aborfield. The arms that are basically the same except for what look like tassels (called ermine) on the chevron are the arms of Sir Edward Bullock, whose arms were officially changed in 1602 to mark his decent from a younger son.