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 SKUBasic SKU
Backend pool sizeup to 1000 instancesup to 100 instances
Backend pool endpointsany 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 Zoneszone-redundant and zonal frontends for inbound and outbound, outbound flows mappings survive zone failure, cross-zone load balancing/
DiagnosticsAzure 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 measurementsAzure Log Analytics for public Load Balancer only, SNAT exhaustion alert, backend pool health count
HA Portsinternal Load Balancer/
Secure by defaultdefault closed for public IP and Load Balancer endpoints and a network security group must be used to explicitly whitelist for traffic to flowdefault open, network security group optional
Outbound connectionsMultiple 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 frontendsInbound and outboundInbound only
Management OperationsMost operations < 30 seconds60-90+ seconds typical
SLA99.99% for data path with two healthy virtual machinesImplicit in VM SLA
PricingCharged based on number of rules, data processed inbound or outbound associated with resourceNo charge