Big data analytics as name suggests deals with complex relational and non relational data bases with different data structures. Analyzing them (not essentially through charts) through analytics such as correlations, forecasts clustering etc is big data analytics. Some of the tools are apache spark, hadoop, hive etc.
Visual data analytics on the other hand doesn't have to be big data and involves performing descriptive and exploratory analysis through visualizations. Some of the tools are BI tools like Tableau, power BI, cognos