My first impulse was to think of pubs as "bars". But that's not really the case. Pubs feel more like a communal living room. I mean, you won't see children in a Texas bar. But, at least in Ireland, pubs are family friendly.
Is there a difference between bars and pubs?
In the UK we don't really refer to any particular establishment as just a "bar". The closest you get are cocktail bars, or wine bars, that specialise in those things. But typically the "bar" is just the location in the establishment where the drinks are served from - whether it's in a theatre, a hotel, a pub, a nightclub etc. We do say things like "I'll meet you in the bar" if referring to a hotel, or theatre, i.e. the part of the establishment where the bar is located. But if it's a pub then we would say "I'll meet you in the pub".
A pub is a type of establishment that has one or more bars, but tends to serve mainly cider/ale/beer/lager on tap (some in bottles), plus a relatively small selection of other drinks (spirits, soft drinks, wines etc). The atmosphere of pubs is also generally different, and much more "olde worlde" than your usual cocktail- or wine-bar. There's a certain style you can often associate with pubs, with regard decor, seating arrangements, etc. They also quite often serve a menu of food, although the extent, quality, and pricing of which varies massively. But then this is probably true of "bars" as well.
As for being family friendly or not, that's more a matter of where the pub is located, and the clientele they want to attract. Some specifically target families (may even have a child activities in the garden) whereas others would very much be a no-go area for them. But to me it would be that the "pub" generally has a hearty and social/communal feel to it compared to a "bar". It's not a clear-cut line, and there are likely some bars that make themselves out to look more like pubs, or pubs that have gone for the modern look.
Hope that helps.