Azure Standard Load Balancer is now generally available, you will not be able to load balance upto a 1000 instances , add any VM to your back-end pools and it’s even locked down by a NSG by default.

For a full comparison list please see below:

referenced from

Standard SKU Basic SKU
Backend pool size up to 1000 instances up to 100 instances
Backend pool endpoints any virtual machine in a single virtual network, including blend of virtual machines, availability sets, virtual machine scale sets. virtual machines in a single availability set or virtual machine scale set
Availability Zones zone-redundant and zonal frontends for inbound and outbound, outbound flows mappings survive zone failure, cross-zone load balancing /
Diagnostics Azure Monitor, multi-dimensional metrics including byte and packet counters, health probe status, connection attempts (TCP SYN), outbound connection health (SNAT successful and failed flows), active data plane measurements Azure Log Analytics for public Load Balancer only, SNAT exhaustion alert, backend pool health count
HA Ports internal Load Balancer /
Secure by default default closed for public IP and Load Balancer endpoints and a network security group must be used to explicitly whitelist for traffic to flow default open, network security group optional
Outbound connections Multiple frontends with per rule opt-out. An outbound scenario must be explicitly created for the virtual machine to be able to use outbound connectivity. VNet Service Endpoints can be reached without outbound connectivity and do not count towards data processed. Any public IP addresses, including Azure PaaS services not available as VNet Service Endpoints, must be reached via outbound connectivity and count towards data processed. When only an internal Load Balancer is serving a virtual machine, outbound connections via default SNAT are not available. Outbound SNAT programming is transport protocol specific based on protocol of the inbound load balancing rule. Single frontend, selected at random when multiple frontends are present. When only internal Load Balancer is serving a virtual machine, default SNAT is used.
Multiple frontends Inbound and outbound Inbound only
Management Operations Most operations < 30 seconds 60-90+ seconds typical
SLA 99.99% for data path with two healthy virtual machines Implicit in VM SLA
Pricing Charged based on number of rules, data processed inbound or outbound associated with resource No charge