The following table highlights the differences between PolyBase and linked server features:
PolyBaseLinked Servers Database scoped objectInstance scoped object Uses ODBC driversUses OLEDB providers Supports read-only operations for all data sources and write to some external data sourcesSupports both read and write operations Queries to remote data source from a single connection can be scaled-outQueries to remote data source from a single connection cannot be scaled-out Predicates pushdown is supportedPredicates pushdown is supported No separate configuration needed for availability groupSeparate configuration needed for each instance in availability group Basic authentication onlyBasic & integrated authentication Suitable for analytic queries processing large number of rowsSuitable for OLTP queries returning single or few rows Queries using external table cannot participate in distributed transactionDistributed queries can participate in distributed transaction